Karner Blue
Encyclopedia
The Karner Blue, Lycaeides melissa samuelis, is a small, blue butterfly
found in small areas of New Jersey
, the Great Lakes
region, southern New Hampshire
, and the Capital District
region of New York
. The butterfly, whose lifecycle depends on the wild blue lupin
e flower (Lupinus perennis
), is classified as an endangered species
. In May 2000, the Canadian Species at Risk Act listed the Karner Blue as being locally extinct
in Canada
. This subspecies
of Lycaeides melissa
was described by novelist Vladimir Nabokov
. It is sometimes placed in the genus
Plebejus.
Local conservation efforts, concentrating on replanting large areas of blue lupine which have been lost to development
(and to fire suppression, which destroys the open, sandy habitat required by blue lupine), are having modest success at encouraging the butterfly's repopulation. The Karner Blue is the official state butterfly of New Hampshire
. The Necedah National Wildlife Refuge
in central Wisconsin
is home to the world's largest population of Karner Blues, which benefit from its vast area of savannah and extensive lupine.
The Karner Blue was first identified and named by novelist and lepidopterist Vladimir Nabokov
. The name originates from Karner
, New York
(located half-way between Albany
and Schenectady
) in the Albany Pine Bush), where it was first discovered. Lupine blooms in late May. There are two generations of Karner Blues per year. The first in late May to mid June. The second from mid-July to mid-August.
In the novel Pnin
, Nabokov describes a score of Karner Blues without naming them.
Although Karner blue butterflies are characteristic of oak savanna
s (Quercus spp.) and pine barrens
(Pinus spp.) habitats, they also occur in frequently disturbed areas such as rights-of-way, old fields, and road margins. In east-central New York, Karner blue butterflies occurred in 3 rights-of-way habitat types: wild lily-of-the-valley-starflower (Maianthemum canadensis-Trientalis borealis), sweetfern-whorled yellow loosestrife (Comptonia peregrina-Lysimachia quadrifolia), and blackberry-sheep sorrel (Rubus spp.-Rumex acetosella). An index of Karner blue population size was highest in the wild lily-of-the-valley-starflower type. In this habitat, mosses (Bryophyta, 6.9%), wild lily-of-the-valley (4.4%), grasses (Poaceae, 4.4%), and starflower (2.1%) had the highest cover. Coverage in the sweetfern-whorled yellow loosestrife type was dominated by grasses (40.9%), sweetfern (12.1%), mosses (9.4%), and whorled yellow loosestrife (5.2%). In the blackberry-sheep sorrel type, the dominants included grasses (22.7%), northern dewberry (Rubus flagellaris, 5.0%), other blackberries (4.8%), and sheep sorrel (4.3%).
Many other factors may influence the quality of wild lupine (Lupinus perennis
) as a Karner blue butterfly food resource. At Indiana Dunes National Lakeshore, wild lupine with Karner blue butterfly feeding damage had significantly larger leaves and longer and thicker stems than plants without feeding damage. In addition, larval length was positively associated with wild lupine height in central Wisconsin. Higher nitrogen concentrations in wild lupine leaves resulted in significantly shorter larval durations in a feeding trial. In 1995 in west-central Wisconsin, significantly more Karner blue butterfly larvae were observed in oak-pine barren plots where mildew infection was delayed compared to areas where wild lupine were infected earlier. However, in a feeding trial larval duration of Karner blue butterflies fed mildew-infected wild lupine was not significantly different from treatments that resulted in the shortest larval durations. Karner blue butterfly fed water-stressed wild lupine had significantly longer larval durations than many treatments including larvae fed flowering wild lupine, shade-grown wild lupine in seed, or mildew-infected wild lupine. Although Karner blue butterflies have been shown to benefit from their association with ants, wild lupine with Karner blue butterfly larvae in the Allegan State Game Area in Michigan were not detectably closer to ant hills than wild lupine without caterpillars.
Adult Karner blue butterflies' preference for open, sunny areas has been well documented. Increased lupine and nectar abundance, higher temperatures allowing for longer activity periods, and ease of finding mates have been suggested as possible reasons for adult preference of open areas.
Adult Karner blue butterfly females are more likely to use shaded habitats than males. Avoiding harassment by males and compromising between greater amounts of wild lupine in open areas and better quality of wild lupine in shaded areas (see below) have been suggested as possible reasons for increased occurrence of females in shade.
Differences between broods have also been observed. In west-central Wisconsin, abundance of spring adults positively correlated with decreasing canopy cover, while correlation with summer adults was very weak. At Indiana Dunes National Lakeshore, cover at late summer oviposition sites was significantly higher than at late spring oviposition sites. In Wisconsin and Minnesota, late spring oviposition sites occurred in partial and closed habitats significantly more than expected based on the number of nectar flowers and the cover and number of wild lupine stems, while summer oviposition sites did not differ significantly from expected. The different brood responses to shade may be due to the direct impact of varying environmental conditions over the course of the season on Karner blue butterflies (see section "Temperature") and the associated effects on wild lupine (see below).
Larvae in shaded habitat apparently have an advantage over those in open areas. The increase in larvae in shaded habitats is likely due to effects of shade on wild lupine.
Shade-grown wild lupine has been shown to provide higher quality larval resource than sun-grown lupine. Several reasons for this have been suggested. An often cited reason for the dependence of larvae, especially 2nd-brood larvae, on shaded habitat is the possibility of early senescence of wild lupine in open areas resulting in a lack of larval food. Shade-grown wild lupine being more nutritious, possibly due to nitrogen content limiting photosynthesis to a greater extent in open areas, was one of several explanations. The size of wild lupine has been positively associated with Karner blue butterfly larval length and amount of feeding damage. In addition, there may be shade-related effects on Karner blue butterflies that are related to the density of wild lupine. Wild lupine are typically more abundant in open areas than in shade. Mildew infection of wild lupine may be increased in denser wild lupine patches. Lower mildew infection rates in shadier areas have been reported. However the implications of mildew infection on Karner blue butterfly are uncertain (see section "Wild lupine"). It has also been suggested that the low density of wild lupine in shadier habitats could provide better larval habitat due to the increased search effort required by predators. This trade-off between lupine quality and quantity is another reason heterogeneous habitat is important for Karner blue butterfly.
On sites in Wisconsin and Minnesota, canopy cover did not have a significant (p>0.06) effect on total numbers of ants, parasitoids, or predators. However, certain species did show trends across canopy cover categories. For instance the ant Formica nitidiventris was only seen in open (≤15% cover) areas, while another ant, Dolichoderus plagiatus was only observed in areas with a dense canopy (≥76% cover). Parasitoids in the genera Phaeogenes and Orthostigma were all seen in closed habitats, while 90% of damsel bugs (Nabicula subcoleoptrata), a potential predator, were observed in open areas. Closed habitats had insignificantly (p=0.116) more parasitoids on average than partial (16%–75% cover) and closed habitats.
Other habitat characteristics: Although Schweitzer asserts that the presence of litter is important to Karner blue butterflies in some years, abundance in a right-of-way in west-central Wisconsin was negatively (p<0.05) related with average litter cover.
In west-central Wisconsin, the amount of Karner blue butterfly larval feeding damage increased with grass cover. A review suggests that grass cover may provide roosting sites for Karner blue butterflies and that 5% cover of tall grass would most likely meet this need.
The effect of temperature can influence the occurrence of Karner blue butterflies in habitats of varying canopy cover. The lower temperatures occurring in partial and shaded habitats of Wisconsin and Minnesota meant that 1st-flight females only had access to these areas for a few hours a day. In contrast, these females could access open habitats an average of 10.5 hours a day. The percent of adults in habitats of varying canopy categories was significantly (p=0.0001) influenced by temperature, with butterflies, especially females, increasing in partial (15-75%) and shaded (>75%) habitats with increasing temperature. In addition, 80% (n=45) of 1st-flight ovipositions when temperatures were cool (68-79 °F, 20-26 °C) were in sun, while only 40% (n=17) of 1st-flight ovipositions in hot temperatures (86-97 °F, 30-36 °C) occurred in the sun. The same trend was observed in 2nd-flight ovipositions. In cool temperatures 65% (n=11) of ovipositions occurred in the sun, while in hot temperatures only 40% (n=37) occurred in the sun.
Temperature also influences Karner blue butterfly phenology and brood success. Weather had strong influence on Karner blue butterfly phenology at Fort McCoy in west-central Wisconsin. In a cool year the 2nd-brood flight began 6 June, while in a warmer year adults were 1st detected on 22 May. In addition, compared to the previous year the flight of the 2nd-brood during the hot year was shortened by 20 days. At Indiana Dunes National Lakeshore, evidence suggests that cool winters negatively impact1st-brood populations and cool summers positively affect 2nd-brood populations. A review suggests that the cover provided by snowpack protects Karner blue butterfly eggs from hatching prematurely or being overheated by direct sunlight. Therefore, short periods of continuous snow cover due to site conditions or mild winters could result in decreased occurrence or smaller populations of Karner blue butterflies.
Size of habitat patches can also influence Karner blue butterfly abundance (see section "Wild lupine"). At the Allegan State Game Area, wild lupine patches occupied by Karner blue butterflies were larger than unoccupied patches. This was also the case at Fort McCoy in Wisconsin. In addition to the effect of amount of wild lupine, a review suggests that it is easier to maintain Karner blue butterfly habitat in larger patches. Lane notes the need to find a balance between having patches of different required habitats within the activity range of Karner blue butterflies and having open areas large enough that they do not become shaded too quickly. Canopy openings with diameters of at least 82 feet (25 m) were recommended based on research at Indiana Dunes National Lakeshore, and research in Wisconsin and Minnesota led to a recommended opening size of 1.5 times the height of adjacent trees. According to a review, subpopulations in habitat patches of less than 0.25 ha (0.62 acres) are vulnerable to extirpation.
The presence of dispersal corridors may assist with Karner blue butterfly dispersal. Karner blue butterflies appear to disperse further in open habitats (see section "Timing of major life history events"). However, there is uncertainty regarding what constitutes a corridor or a barrier to dispersal. Creation of corridors with both lupine for larvae and nectar species for adults may be useful in connecting habitat patches.
A wide range of values related to Karner blue butterfly recruitment have been reported. Adult Karner blue sex ratios vary from 1 male to 1.44 females to 2 males to 1 female. Wild caught Karner blue butterfly females have been observed to lay from 7.7 to 83 eggs on average. Reported percentages of eggs that reach adulthood under controlled conditions vary from 21.4% to 75.2%. In the wild, loss of eggs may be substantial.
Karner blue butterflies do not typically move vary far, with males usually moving further than females, with most studies showing average distances moved by individual butterflies of well under 1000 feet (304.8 m).
spp.), spined soldier bugs, and ants (Formica
spp.) have been observed removing larvae, and the ant Monomorium emarginatum has been seen chewing on Karner blue butterfly eggs. There is currently no explanation for the removal of larvae or chewing of eggs by some of the same ant species that tend larvae. Other potential predators of Karner blue butterfly larvae include green lacewings, soldier beetles, and damsel bugs. Predators of adult Karner blue butterflies include dragonflies, robber flies, ambush bugs
(Phymatidae) and spiders, such as crab spiders. Assassin bugs (Reduviidae) are also likely predators of adult Karner blue butterflies.
Other likely predators include white-tailed deer
and birds. Incidental predation of Karner blue butterfly eggs, larvae, and pupae by white-tailed deer grazing on wild lupine can be substantial.
Wasps are the most commonly reported parasitoids of Karner blue butterflies. A tachinid fly, Aplomya theclarum, has also been listed as a Karner blue butterfly parasite. Two wasps, one from the Trichogrammatidae
family and another tentatively identified as a member of the Eulophidae
family, are suspected to parasitize Karner blue butterfly eggs.
-bear oak
(Pinus rigida-Quercus ilicifolia) habitat in New York
, significantly more larvae tended by ants survived (67%) than untended larvae (38%). The 19 ant species tending Karner blue butterfly larvae were from the subfamilies Formicinae
, Myrmicinae
, and Dolichoderinae
, which are the most common in the area. The species of ant is likely to influence the degree of benefit gained by Karner blue butterfly larvae. At sites in Wisconsin and Minnesota, ant tending rates increased significantly with increasing larval age. In a study of the effect of different experimental feeding treatments, Karner blue butterfly larvae tended by ants had one of the shortest observed larval durations and gained the most weight for the amount of lupine eaten.
Articles that address Karner blue butterfly sampling methodology include. Swengel found that surveys for Karner blue butterfly adults appeared more efficient than those for larvae. Evidence of different catchability and/or detectability of male and female Karner blue butterflies led King to suggest calculating male and female population sizes separately. General descriptions of Karner blue butterfly rearing methods and translocation/ reintroduction techniques are available.
A wide variety of management techniques can be compatible with maintaining Karner blue butterfly populations when attention is paid to implementing them at appropriate times and at intensities, scales, and frequencies that Karner blue butterflies can tolerate. For example, mowing can maintain open areas with little to no detrimental effect on Karner blue butterflies on sites where burning is impractical or in areas too small to support populations of Karner blue butterflies likely to survive a burn. On restored oak savanna sites in south-central Wisconsin, no significant (p=0.924) differences were detected between Karner blue butterfly densities on sites burned in summer, sites mowed in August, and control sites. Mowing with a blade height >4 inches (10 cm) should be performed annually or biennially in the fall or winter and clippings should be left in place. Effects of mowing, burning, and other management techniques and land uses on the average number of Karner blue butterflies observed per survey hour are included in. Recommendations on the use of a wide range of management techniques such as thinning, rotational grazing, and planting of wild lupine and/or nectar species can be found in.
According to reviews and general field observations, management activities that are typically harmful to Karner blue butterflies include management that increases deer and/or grouse populations, close-cropped grazing, frequent or poorly-timed mowing, plowing, use of herbicides that kill lupine or nectar plants, and use of pesticides that are detrimental to Karner blue butterflies, ants they associate with, or pollinators of species they use for nectar. Information on the impacts of an insecticide on Karner blue butterflies and some herbicides on Karner blue butterflies as well as lupine and nectar species are available. According to the Karner blue butterfly recovery plan, management activities that can have a detrimental effect should be timed to allow at least 2 generations between repeat treatments and, if possible, critical subpopulations should be divided into discrete management units.
Butterfly
A butterfly is a mainly day-flying insect of the order Lepidoptera, which includes the butterflies and moths. Like other holometabolous insects, the butterfly's life cycle consists of four parts: egg, larva, pupa and adult. Most species are diurnal. Butterflies have large, often brightly coloured...
found in small areas of New Jersey
New Jersey
New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...
, the Great Lakes
Great Lakes
The Great Lakes are a collection of freshwater lakes located in northeastern North America, on the Canada – United States border. Consisting of Lakes Superior, Michigan, Huron, Erie, and Ontario, they form the largest group of freshwater lakes on Earth by total surface, coming in second by volume...
region, southern New Hampshire
New Hampshire
New Hampshire is a state in the New England region of the northeastern United States of America. The state was named after the southern English county of Hampshire. It is bordered by Massachusetts to the south, Vermont to the west, Maine and the Atlantic Ocean to the east, and the Canadian...
, and the Capital District
Capital District
New York's Capital District, also known as the Capital Region, is a region in upstate New York that generally refers to the four counties surrounding Albany, the capital of the state: Albany County, Schenectady County, Rensselaer County, and Saratoga County...
region of New York
New York
New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...
. The butterfly, whose lifecycle depends on the wild blue lupin
Lupin
Lupinus, commonly known as Lupins or lupines , is a genus in the legume family . The genus comprises about 280 species , with major centers of diversity in South and western North America , and the Andes and secondary centers in the Mediterranean region and Africa Lupinus, commonly known as Lupins...
e flower (Lupinus perennis
Lupinus perennis
Lupinus perennis is a medicinal plant in the Fabaceae family...
), is classified as an endangered species
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
. In May 2000, the Canadian Species at Risk Act listed the Karner Blue as being locally extinct
Local extinction
Local extinction, also known as extirpation, is the condition of a species which ceases to exist in the chosen geographic area of study, though it still exists elsewhere...
in Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
. This subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
of Lycaeides melissa
Lycaeides melissa
The Melissa Blue is a butterfly of the Lycaenidae family. It is found in Western North America, from Canada to Mexico. The Karner Blue is a subspecies of the Melissa Blue.The wingspan is 22–35 mm...
was described by novelist Vladimir Nabokov
Vladimir Nabokov
Vladimir Vladimirovich Nabokov was a multilingual Russian novelist and short story writer. Nabokov wrote his first nine novels in Russian, then rose to international prominence as a master English prose stylist...
. It is sometimes placed in the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Plebejus.
Local conservation efforts, concentrating on replanting large areas of blue lupine which have been lost to development
Urbanization
Urbanization, urbanisation or urban drift is the physical growth of urban areas as a result of global change. The United Nations projected that half of the world's population would live in urban areas at the end of 2008....
(and to fire suppression, which destroys the open, sandy habitat required by blue lupine), are having modest success at encouraging the butterfly's repopulation. The Karner Blue is the official state butterfly of New Hampshire
New Hampshire
New Hampshire is a state in the New England region of the northeastern United States of America. The state was named after the southern English county of Hampshire. It is bordered by Massachusetts to the south, Vermont to the west, Maine and the Atlantic Ocean to the east, and the Canadian...
. The Necedah National Wildlife Refuge
Necedah National Wildlife Refuge
Necedah National Wildlife Refuge is a National Wildlife Refuge located in northern Juneau County, Wisconsin near the village of Necedah. It was established in 1939 and is famous as the northern nesting site for reintroduction of an eastern United States population of the endangered Whooping Crane...
in central Wisconsin
Wisconsin
Wisconsin is a U.S. state located in the north-central United States and is part of the Midwest. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake Michigan to the east, Michigan to the northeast, and Lake Superior to the north. Wisconsin's capital is...
is home to the world's largest population of Karner Blues, which benefit from its vast area of savannah and extensive lupine.
The Karner Blue was first identified and named by novelist and lepidopterist Vladimir Nabokov
Vladimir Nabokov
Vladimir Vladimirovich Nabokov was a multilingual Russian novelist and short story writer. Nabokov wrote his first nine novels in Russian, then rose to international prominence as a master English prose stylist...
. The name originates from Karner
Karner, New York
Karner is a hamlet of the town of Colonie, Albany County, New York. Once called Center Station it was a stop along the New York Central Railroad that became famous for being the site where the Karner Blue butterfly was first identified.-History:...
, New York
New York
New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...
(located half-way between Albany
Albany, New York
Albany is the capital city of the U.S. state of New York, the seat of Albany County, and the central city of New York's Capital District. Roughly north of New York City, Albany sits on the west bank of the Hudson River, about south of its confluence with the Mohawk River...
and Schenectady
Schenectady, New York
Schenectady is a city in Schenectady County, New York, United States, of which it is the county seat. As of the 2010 census, the city had a population of 66,135...
) in the Albany Pine Bush), where it was first discovered. Lupine blooms in late May. There are two generations of Karner Blues per year. The first in late May to mid June. The second from mid-July to mid-August.
In the novel Pnin
Pnin
Pnin is Vladimir Nabokov's 13th novel and his fourth written in English; it was published in 1957.-Plot summary:The book's eponymous protagonist, Timofey Pavlovich Pnin, is a Russian-born professor living in the United States...
, Nabokov describes a score of Karner Blues without naming them.
Description
The male and female of this small (wingspan of about one inch) butterfly are different in appearance. The topside of the male is silvery or dark blue with narrow black margins. The female is grayish brown, especially on the outer portions of the wings, to blue on the topside, with irregular bands of orange crescents inside the narrow black border. The underside of both sexes is gray with a continuous band of orange crescents along the edges of both wings and with scattered black spots circled with white.Distribution and habitat
The Karner blue butterfly occurs in isolated populations in eastern Minnesota, Wisconsin, Indiana, Michigan, and New York. Reintroductions have been initiated in Ohio and New Hampshire. The Karner blue butterfly appears extirpated from Iowa, Illinois, Pennsylvania, Massachusetts, Maine, and Ontario.Although Karner blue butterflies are characteristic of oak savanna
Oak savanna
An oak savanna is a type of savanna, or lightly forested grassland, where oaks are the dominant tree species. These savannas were maintained historically through wildfires set by lightning, grazing, low precipitation, poor soil, and/or fires set by Native Americans...
s (Quercus spp.) and pine barrens
Pine barrens
Pine barrens, pine plains, sand plains, or pinelands occur throughout the northeastern U.S. from New Jersey to Maine as well as the Midwest and Canada....
(Pinus spp.) habitats, they also occur in frequently disturbed areas such as rights-of-way, old fields, and road margins. In east-central New York, Karner blue butterflies occurred in 3 rights-of-way habitat types: wild lily-of-the-valley-starflower (Maianthemum canadensis-Trientalis borealis), sweetfern-whorled yellow loosestrife (Comptonia peregrina-Lysimachia quadrifolia), and blackberry-sheep sorrel (Rubus spp.-Rumex acetosella). An index of Karner blue population size was highest in the wild lily-of-the-valley-starflower type. In this habitat, mosses (Bryophyta, 6.9%), wild lily-of-the-valley (4.4%), grasses (Poaceae, 4.4%), and starflower (2.1%) had the highest cover. Coverage in the sweetfern-whorled yellow loosestrife type was dominated by grasses (40.9%), sweetfern (12.1%), mosses (9.4%), and whorled yellow loosestrife (5.2%). In the blackberry-sheep sorrel type, the dominants included grasses (22.7%), northern dewberry (Rubus flagellaris, 5.0%), other blackberries (4.8%), and sheep sorrel (4.3%).
Wild lupine
Several studies have found a positive relationship between measures of wild lupine and Karner blue butterfly abundance. However, available evidence suggests that senescent wild lupine is a poor larval food source. The effects of other phenological stages are more ambiguous. In west-central Wisconsin, Karner blue butterfly abundance was negatively associated with the abundance of reproductive lupine and positively related with the frequency of immature wild lupine. However, a feeding trial found that Karner blue butterfly fed 1st year wild lupine had one of the lowest survival rates observed and significantly longer larval durations than larvae fed older wild lupine that did not flower, was flowering, had recently flowered, or was grown in shade and was in seed. In addition, on sites in Wisconsin and Minnesota, the number of 1st flight oviposition sites on nonreproductive and reproductive wild lupine was similar.Many other factors may influence the quality of wild lupine (Lupinus perennis
Lupinus perennis
Lupinus perennis is a medicinal plant in the Fabaceae family...
) as a Karner blue butterfly food resource. At Indiana Dunes National Lakeshore, wild lupine with Karner blue butterfly feeding damage had significantly larger leaves and longer and thicker stems than plants without feeding damage. In addition, larval length was positively associated with wild lupine height in central Wisconsin. Higher nitrogen concentrations in wild lupine leaves resulted in significantly shorter larval durations in a feeding trial. In 1995 in west-central Wisconsin, significantly more Karner blue butterfly larvae were observed in oak-pine barren plots where mildew infection was delayed compared to areas where wild lupine were infected earlier. However, in a feeding trial larval duration of Karner blue butterflies fed mildew-infected wild lupine was not significantly different from treatments that resulted in the shortest larval durations. Karner blue butterfly fed water-stressed wild lupine had significantly longer larval durations than many treatments including larvae fed flowering wild lupine, shade-grown wild lupine in seed, or mildew-infected wild lupine. Although Karner blue butterflies have been shown to benefit from their association with ants, wild lupine with Karner blue butterfly larvae in the Allegan State Game Area in Michigan were not detectably closer to ant hills than wild lupine without caterpillars.
Canopy cover
Due to effects of environmental variation and differing requirements among life stages, broods, and sexes, Karner blue butterflies require a mosaic of sun and shade.Adult Karner blue butterflies' preference for open, sunny areas has been well documented. Increased lupine and nectar abundance, higher temperatures allowing for longer activity periods, and ease of finding mates have been suggested as possible reasons for adult preference of open areas.
Adult Karner blue butterfly females are more likely to use shaded habitats than males. Avoiding harassment by males and compromising between greater amounts of wild lupine in open areas and better quality of wild lupine in shaded areas (see below) have been suggested as possible reasons for increased occurrence of females in shade.
Differences between broods have also been observed. In west-central Wisconsin, abundance of spring adults positively correlated with decreasing canopy cover, while correlation with summer adults was very weak. At Indiana Dunes National Lakeshore, cover at late summer oviposition sites was significantly higher than at late spring oviposition sites. In Wisconsin and Minnesota, late spring oviposition sites occurred in partial and closed habitats significantly more than expected based on the number of nectar flowers and the cover and number of wild lupine stems, while summer oviposition sites did not differ significantly from expected. The different brood responses to shade may be due to the direct impact of varying environmental conditions over the course of the season on Karner blue butterflies (see section "Temperature") and the associated effects on wild lupine (see below).
Larvae in shaded habitat apparently have an advantage over those in open areas. The increase in larvae in shaded habitats is likely due to effects of shade on wild lupine.
Shade-grown wild lupine has been shown to provide higher quality larval resource than sun-grown lupine. Several reasons for this have been suggested. An often cited reason for the dependence of larvae, especially 2nd-brood larvae, on shaded habitat is the possibility of early senescence of wild lupine in open areas resulting in a lack of larval food. Shade-grown wild lupine being more nutritious, possibly due to nitrogen content limiting photosynthesis to a greater extent in open areas, was one of several explanations. The size of wild lupine has been positively associated with Karner blue butterfly larval length and amount of feeding damage. In addition, there may be shade-related effects on Karner blue butterflies that are related to the density of wild lupine. Wild lupine are typically more abundant in open areas than in shade. Mildew infection of wild lupine may be increased in denser wild lupine patches. Lower mildew infection rates in shadier areas have been reported. However the implications of mildew infection on Karner blue butterfly are uncertain (see section "Wild lupine"). It has also been suggested that the low density of wild lupine in shadier habitats could provide better larval habitat due to the increased search effort required by predators. This trade-off between lupine quality and quantity is another reason heterogeneous habitat is important for Karner blue butterfly.
On sites in Wisconsin and Minnesota, canopy cover did not have a significant (p>0.06) effect on total numbers of ants, parasitoids, or predators. However, certain species did show trends across canopy cover categories. For instance the ant Formica nitidiventris was only seen in open (≤15% cover) areas, while another ant, Dolichoderus plagiatus was only observed in areas with a dense canopy (≥76% cover). Parasitoids in the genera Phaeogenes and Orthostigma were all seen in closed habitats, while 90% of damsel bugs (Nabicula subcoleoptrata), a potential predator, were observed in open areas. Closed habitats had insignificantly (p=0.116) more parasitoids on average than partial (16%–75% cover) and closed habitats.
Nectar species
Nectar availability is likely to influence Karner blue butterfly abundance. In a right-of-way in west-central Wisconsin, the frequency that Karner blue butterflies stayed in an area between recaptures was significantly (p<0.05) positively related to percent cover of nectar flowers such as Canadian horseweed (Conyza canadensis var. canadensis) and spotted beebalm (Monarda punctata). Preliminary results from a study in southeastern Minnesota suggest that openings where Karner blue butterflies were detected tended to have more flowering nectar species. In Michigan, more Karner blue butterflies were observed on sites with more nectaring plants, especially butterfly milkweed (Asclepias tuberosa). As discussed in Canopy cover, nectar species increase in open habitats. For instance, at Fort McCoy in west-central Wisconsin, all the nectar species listed for Karner blue butterflies require either full or partial sun. In addition, treatments such as cutting with or without herbicides, herbicide application alone, or mowing at varying intervals resulted in a significant (p<0.01) increase in the number and cover of nectar species. See section "Food habits" for species that Karner blue butterflies use as nectar sources.Other habitat characteristics: Although Schweitzer asserts that the presence of litter is important to Karner blue butterflies in some years, abundance in a right-of-way in west-central Wisconsin was negatively (p<0.05) related with average litter cover.
In west-central Wisconsin, the amount of Karner blue butterfly larval feeding damage increased with grass cover. A review suggests that grass cover may provide roosting sites for Karner blue butterflies and that 5% cover of tall grass would most likely meet this need.
Disturbance
Karner blue butterflies may be associated with disturbance. Although results may have been biased by a significant (p=0.009) positive correlation (r=0.2173) between patch area and number of disturbances (such as burning, vehicle traffic, and thinning and clearing), patches in a right-of-way in west-central Wisconsin occupied by Karner blue butterflies had a greater frequency of disturbance than unoccupied patches (p≤0.0125). In the same area, the abundance of the Karner blue butterfly spring brood was positively related to trails, and the percent of lupine stems with larval feeding damage was significantly (p<0.05) greater in areas disturbed by military vehicle traffic.Temperature
Karner blue butterflies are directly affected by temperature. A laboratory investigation of temperature on Karner blue butterfly found that flight typically begins at 76 °F (24.6 °C) for females and 80 °F (26.4 °C) for males (p=0.25). Signs of heat stress started at 96 °F (35.6 °C) for females and 98 °F (36.8 °C) for males (p=0.25). In pine-oak barrens in Wisconsin, observation rates of Karner blue butterflies increased significantly (p=0.000) with increasing temperature.The effect of temperature can influence the occurrence of Karner blue butterflies in habitats of varying canopy cover. The lower temperatures occurring in partial and shaded habitats of Wisconsin and Minnesota meant that 1st-flight females only had access to these areas for a few hours a day. In contrast, these females could access open habitats an average of 10.5 hours a day. The percent of adults in habitats of varying canopy categories was significantly (p=0.0001) influenced by temperature, with butterflies, especially females, increasing in partial (15-75%) and shaded (>75%) habitats with increasing temperature. In addition, 80% (n=45) of 1st-flight ovipositions when temperatures were cool (68-79 °F, 20-26 °C) were in sun, while only 40% (n=17) of 1st-flight ovipositions in hot temperatures (86-97 °F, 30-36 °C) occurred in the sun. The same trend was observed in 2nd-flight ovipositions. In cool temperatures 65% (n=11) of ovipositions occurred in the sun, while in hot temperatures only 40% (n=37) occurred in the sun.
Temperature also influences Karner blue butterfly phenology and brood success. Weather had strong influence on Karner blue butterfly phenology at Fort McCoy in west-central Wisconsin. In a cool year the 2nd-brood flight began 6 June, while in a warmer year adults were 1st detected on 22 May. In addition, compared to the previous year the flight of the 2nd-brood during the hot year was shortened by 20 days. At Indiana Dunes National Lakeshore, evidence suggests that cool winters negatively impact1st-brood populations and cool summers positively affect 2nd-brood populations. A review suggests that the cover provided by snowpack protects Karner blue butterfly eggs from hatching prematurely or being overheated by direct sunlight. Therefore, short periods of continuous snow cover due to site conditions or mild winters could result in decreased occurrence or smaller populations of Karner blue butterflies.
Landscape effects
Karner blue butterflies are dependant on heterogeneous habitat as it provides the varied requirements of different Karner blue butterfly broods, sexes, and life stages over a wide range of environmental conditions. Research at Indiana Dunes National Lakeshore led to recommendations for canopy openings for adult males and nectaring of both sexes, as well as areas with 30-60% cover for ovipositing females. In the Allegan State Game Area, wild lupine patches occupied by Karner blue butterflies had higher density of edge habitats that unoccupied wild lupine patches. In west-central Wisconsin the importance of shaded habitat led to a recommendation that 20% to 40% of Karner blue butterfly habitat provide shaded lupine and that 1/3 have >60% canopy cover with succession in these dense areas allowed to progress to complete closure. Maxwell also suggests avoiding any management that would result in habitat homogenization. The Karner blue butterfly recovery team mentions the importance of a wide range of aspects, hydrology, microtopography as well canopy cover (0-90%) in conserving the Karner blue butterfly. However, Karner blue populations can persist in relatively homogenous habitats. For instance, a population has persisted at the Saratoga Airport in New York in open habitat maintained by regular mowing. More information on the habitat characteristics, environmental conditions, and/or geographic variability in habitat requirements that facilitate Karner blue butterfly's persistence in these areas is needed.Size of habitat patches can also influence Karner blue butterfly abundance (see section "Wild lupine"). At the Allegan State Game Area, wild lupine patches occupied by Karner blue butterflies were larger than unoccupied patches. This was also the case at Fort McCoy in Wisconsin. In addition to the effect of amount of wild lupine, a review suggests that it is easier to maintain Karner blue butterfly habitat in larger patches. Lane notes the need to find a balance between having patches of different required habitats within the activity range of Karner blue butterflies and having open areas large enough that they do not become shaded too quickly. Canopy openings with diameters of at least 82 feet (25 m) were recommended based on research at Indiana Dunes National Lakeshore, and research in Wisconsin and Minnesota led to a recommended opening size of 1.5 times the height of adjacent trees. According to a review, subpopulations in habitat patches of less than 0.25 ha (0.62 acres) are vulnerable to extirpation.
Dispersal
Given their typically short dispersal distance, the spatial arrangement of habitat is important to the conservation of the Karner blue butterfly. Distance between the various types of habitat required by Karner blue butterflies is likely an influential landscape attribute. Lane suggests that suitable Karner blue butterfly habitat occurs in areas where open and closed canopies occur within a 590-foot (180 m) diameter. Maxwell recommends considering the amount of shaded wild lupine habitat within the dispersal distance of Karner blue butterfly when reducing overstory. Many investigators stress the importance of habitat patches being closely spaced. For instance, at sites in west-central Wisconsin, the average distance from an occupied wild lupine patch to another occupied patch was significantly (p=0.002) shorter (709 feet, 216 m) than to an unoccupied patch (1,155 feet, 352 m). Wild lupine patches in the same area that were occupied by Karner blue butterflies were also surrounded by a relatively low percentage of unoccupied patches. In addition, wild lupine patches in the Allegan State Game Area that were occupied by Karner blue butterflies were closer to other occupied patches than wild lupine patches without Karner blue butterflies. This led to the recommendation that habitat patches be within 230 feet (70 m) of each other. Isolation of habitat patches has been suggested as a reason for lack of Karner blue butterfly presence on sites in New York. In addition, studies of Karner blue butterfly dispersal have led to recommended distance between patches of ≤980 feet (300 m) to allow for dispersal and management units no wider than 1,300 to 1,600 feet (400–500 m) to improve recolonization of treated areas.The presence of dispersal corridors may assist with Karner blue butterfly dispersal. Karner blue butterflies appear to disperse further in open habitats (see section "Timing of major life history events"). However, there is uncertainty regarding what constitutes a corridor or a barrier to dispersal. Creation of corridors with both lupine for larvae and nectar species for adults may be useful in connecting habitat patches.
Life history and reproduction
Karner blue butterflies have two broods per year, following wild lupine (Lupinus perennis) phenology quite closely. Eggs laid by Karner blue butterflies in late summer overwinter and hatch in mid- to late April. Development from egg through four larval instars and pupation takes from 25 to 60 days. The average lifespan of adult Karner blue butterflies has been reported at between 3 and 5 days. The first Karner blue butterfly flight generally occurs sometime between mid-May and mid-June, with males typically appearing earlier than females. First flight females lay the vast majority of their eggs on wild lupine. These eggs develop into the adults of the second Karner blue butterfly flight, which generally occurs in July and August. Although always near a wild lupine plant, second brood females lay more eggs on grasses, other plants, and litter than 1st brood females. The 2nd flight is typically two to four times the size of the first flight. However, the first flight of Karner blue butterflies can be larger than the second. Timing and size of both flights can exhibit substantial variation, depending on local weather conditions among other factors.A wide range of values related to Karner blue butterfly recruitment have been reported. Adult Karner blue sex ratios vary from 1 male to 1.44 females to 2 males to 1 female. Wild caught Karner blue butterfly females have been observed to lay from 7.7 to 83 eggs on average. Reported percentages of eggs that reach adulthood under controlled conditions vary from 21.4% to 75.2%. In the wild, loss of eggs may be substantial.
Karner blue butterflies do not typically move vary far, with males usually moving further than females, with most studies showing average distances moved by individual butterflies of well under 1000 feet (304.8 m).
Food habits
Wild lupine is the sole larval food source of the Karner Blue butterfly. Adult Karner blue butterflies obtain nectar from several native and nonnative species. Karner blue butterflies have been reported feeding on the nectar of 41 different species in a single study in west-central Wisconsin. Broods differ significantly in the species used for nectaring, likely due to differences in their phenology. Several blackberries have been documented as food sources for the spring brood, while spotted beebalm, white sweetclover (Melilotus alba), and flowering spurge (Euphorbia corollata), are widely cited sources of nectar in the summer. Common cinquefoil (Potentilla simplex) is used as a nectar species for both broods. Karner blue butterflies' preferred nectar species may include butterfly weed in New York and Michigan and lyrate rockcress (Arabis lyrata), lanceleaf tickseed (Coreopsis lanceolata), white sweetclover, and northern dewberry at Indiana Dunes National Lakeshore. Differences in nectar species used between male and female Karner blue butterflies and across locations have been reported. Other often mentioned nectar sources include New Jersey tea (Ceanothus americanus), wild lupine, goldenrods (Solidago spp.), and spotted knapweed (Centaurea maculosa).Predators
Spiders and many insects are the major predators of Karner blue butterflies. The seven-spotted lady beetle is one of the few confirmed predators of Karner blue butterfly larvae. Paper wasps (PolistesPolistes
Wasps of the cosmopolitan genus Polistes are the most familiar of the polistine wasps, and are the most common type of paper wasp. It is also the single largest genus within the family Vespidae, with over 300 recognized species and subspecies...
spp.), spined soldier bugs, and ants (Formica
Formica
Formica is a genus of ants of the family Formicidae, commonly known as wood ants, mound ants, or field ants. Formica is the type genus of the Formicidae, and of the subfamily Formicinae...
spp.) have been observed removing larvae, and the ant Monomorium emarginatum has been seen chewing on Karner blue butterfly eggs. There is currently no explanation for the removal of larvae or chewing of eggs by some of the same ant species that tend larvae. Other potential predators of Karner blue butterfly larvae include green lacewings, soldier beetles, and damsel bugs. Predators of adult Karner blue butterflies include dragonflies, robber flies, ambush bugs
Phymatinae
Insects in the subfamily Phymatidae are commonly called ambush bugs after their habit of lying in wait for prey relying on their superb camouflage. Armed with raptorial forelegs, ambush bugs routinely capture prey ten or more times their own size. They form a subgroup within the assassin...
(Phymatidae) and spiders, such as crab spiders. Assassin bugs (Reduviidae) are also likely predators of adult Karner blue butterflies.
Other likely predators include white-tailed deer
White-tailed Deer
The white-tailed deer , also known as the Virginia deer or simply as the whitetail, is a medium-sized deer native to the United States , Canada, Mexico, Central America, and South America as far south as Peru...
and birds. Incidental predation of Karner blue butterfly eggs, larvae, and pupae by white-tailed deer grazing on wild lupine can be substantial.
Wasps are the most commonly reported parasitoids of Karner blue butterflies. A tachinid fly, Aplomya theclarum, has also been listed as a Karner blue butterfly parasite. Two wasps, one from the Trichogrammatidae
Trichogrammatidae
The family Trichogrammatidae are tiny wasps in the Chalcidoidea that include some of the smallest of all insects, with most species having adults less than 1 mm in length. There are over 840 species in ca. 80 genera worldwide. Trichogrammatids parasitize the eggs of many different orders of insects...
family and another tentatively identified as a member of the Eulophidae
Eulophidae
Eulophidae is a large family of hymenopteran insects, with over 4,300 described species in some 300 genera . The family as presently defined also includes the genus Elasmus, which was previously treated as a separate family, "Elasmidae", and is now treated as a subfamily of Eulophidae...
family, are suspected to parasitize Karner blue butterfly eggs.
Mutualism with ants
Karner blue butterfly larvae benefit from a facultative, mutualistic relationship with several ant species. In pitch pinePitch Pine
The Pitch Pine, Pinus rigida, is a small-to-medium sized pine, native to eastern North America. This species occasionally hybridizes with other pine species such as Loblolly Pine , Shortleaf Pine , and Pond Pine The Pitch Pine, Pinus rigida, is a small-to-medium sized (6-30 meters or 20-100 feet)...
-bear oak
Bear Oak
Quercus ilicifolia, commonly known as Bear Oak or Scrub Oak, is a small shrubby oak native to the Northeastern United States and Southeastern Canada.-References:**...
(Pinus rigida-Quercus ilicifolia) habitat in New York
New York
New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...
, significantly more larvae tended by ants survived (67%) than untended larvae (38%). The 19 ant species tending Karner blue butterfly larvae were from the subfamilies Formicinae
Formicinae
Formicinae is a subfamily within the Formicidae containing ants of moderate evolutionary development.Formicines retain some primitive features such as the presence of cocoons around pupae, the presence of ocelli in workers, and little tendency toward reduction of palp or antennal segmentation in...
, Myrmicinae
Myrmicinae
Myrmicinae is a subfamily of ants. There are about 140 genera within the group, with the family being cosmopolitan. The pupae lack cocoons. Some species retain a functional sting. The petioles of Myrmicinae consist of two nodes...
, and Dolichoderinae
Dolichoderinae
Dolichoderinae is a subfamily of ants, which includes species such as the Argentine ant , the erratic ant, the odorous house ant, and the cone ant. This subfamily is distinguished by having a single petiole and a slit-like orifice, rather than the round acidopore encircled by hairs that typifies...
, which are the most common in the area. The species of ant is likely to influence the degree of benefit gained by Karner blue butterfly larvae. At sites in Wisconsin and Minnesota, ant tending rates increased significantly with increasing larval age. In a study of the effect of different experimental feeding treatments, Karner blue butterfly larvae tended by ants had one of the shortest observed larval durations and gained the most weight for the amount of lupine eaten.
Management considerations
According to reviews, habitat loss through direct conversion to other land uses and through succession are considered the major causes of the decline of the Karner blue butterfly. At the time of this writing (2006), two reviews summarize the recent status of Karner blue butterfly across its range. Recovery criteria are addressed by, while Christenson and Lentz discuss lessons learned developing a statewide Habitat Conservation Plan for Wisconsin.Articles that address Karner blue butterfly sampling methodology include. Swengel found that surveys for Karner blue butterfly adults appeared more efficient than those for larvae. Evidence of different catchability and/or detectability of male and female Karner blue butterflies led King to suggest calculating male and female population sizes separately. General descriptions of Karner blue butterfly rearing methods and translocation/ reintroduction techniques are available.
A wide variety of management techniques can be compatible with maintaining Karner blue butterfly populations when attention is paid to implementing them at appropriate times and at intensities, scales, and frequencies that Karner blue butterflies can tolerate. For example, mowing can maintain open areas with little to no detrimental effect on Karner blue butterflies on sites where burning is impractical or in areas too small to support populations of Karner blue butterflies likely to survive a burn. On restored oak savanna sites in south-central Wisconsin, no significant (p=0.924) differences were detected between Karner blue butterfly densities on sites burned in summer, sites mowed in August, and control sites. Mowing with a blade height >4 inches (10 cm) should be performed annually or biennially in the fall or winter and clippings should be left in place. Effects of mowing, burning, and other management techniques and land uses on the average number of Karner blue butterflies observed per survey hour are included in. Recommendations on the use of a wide range of management techniques such as thinning, rotational grazing, and planting of wild lupine and/or nectar species can be found in.
According to reviews and general field observations, management activities that are typically harmful to Karner blue butterflies include management that increases deer and/or grouse populations, close-cropped grazing, frequent or poorly-timed mowing, plowing, use of herbicides that kill lupine or nectar plants, and use of pesticides that are detrimental to Karner blue butterflies, ants they associate with, or pollinators of species they use for nectar. Information on the impacts of an insecticide on Karner blue butterflies and some herbicides on Karner blue butterflies as well as lupine and nectar species are available. According to the Karner blue butterfly recovery plan, management activities that can have a detrimental effect should be timed to allow at least 2 generations between repeat treatments and, if possible, critical subpopulations should be divided into discrete management units.
Nectar
Given the wide range of nectar species used by Karner blue butterfly (see section "Food habits"), planting several often used or preferred nectar species is favored over selecting 1 or 2 specific species. Species selection should attempt to provide nectar sources in both open and partially shaded conditions throughout the growing season despite yearly variation in environmental conditions. Planting nonnative nectar sources is discouraged due to their potential impacts on native food sources, especially wild lupine.Heterogeneity
Heterogeneity is an important feature of Karner blue butterfly habitat. Specific recommendations regarding the spatial arrangement of the various required habitat types and Karner blue butterfly habitat patches are discussed in Landscape effects. Creation and rotation of management units should incorporate this information as well as data on Karner blue butterfly movement (see section "Timing of major life history events"). Bidwell recommends management units be a maximum of 1,300 to 1,600 feet (400–500 m) wide to improve recolonization from neighboring areas. Depending on the available and surrounding habitat, managing for heterogeneity could mean implementing a wide range of techniques.External links
- U.S. Fish and Wildlife Service (Midwest Region) Karner Blue Butterfly page
- Karner blue butterfly This site from the Wisconsin Department of Natural Resources contains conservation information, identification tips, plant species that attract and nurture Karner blues, and much more.
- NY DEC article on the Karner Blue
- Karner Blue Butterfly (Lycaeides melissa samuelis)
- Karner blue butterfly This site from the Wisconsin Department of Natural Resources contains conservation information, identification tips, plant species that attract and nurture Karner blues, and much more.
- Rhapsody In Blue The Karner blue butterfly makes a comeback
- The Return of The Karner Blue in Ohio
- Karner Blue for New York State Butterfly An effort to have the Karner Blue declared the official NY state butterfly and how it will help prevent extinction of the species
- http://www.dnr.wi.gov/forestry/karner/ The most successful Karner blue butterfly conservation effort is in Wisconsin.