Latrodectus geometricus
Encyclopedia
The spider Latrodectus geometricus, commonly known as the brown widow, grey widow, or geometric button spider, is one of the widow spiders in the genus Latrodectus. As such, it is a "cousin" to the more famous Latrodectus mactans. The brown widow is found in parts of the southeastern
, southern
and southwestern
United States
(including Florida
, Alabama
, California
, Kansas
, Oklahoma, Nevada
, Louisiana
, Mississippi
, Georgia
, South Carolina, North Carolina, Tennessee
, Ohio
, Michigan
, Arizona
, New Mexico
and Texas
); outside of the U.S. there are reports in parts of Australia
, Afghanistan
, Japan
, South Africa
and Cyprus
. The origin of this species is uncertain, as specimens were independently discovered in both Africa
and the Americas
. They are usually found around buildings in tropical areas.
L. geometricus is generally lighter in color than the black widow
species—the color can range from tan to dark brown to black, with shades of grey also possible. Like the black widow species in the United States
, L. geometricus has a prominent "hourglass" marking on the underside of the abdomen; the brown widow's hourglass, however, is usually a vivid orange or a yellowish color. Unlike the black widow, L. geometricus has a black-and-white "geometric" pattern on the dorsal side of its abdomen. Although the Latin name comes from this pattern, a spider's coloring can and does darken over time and the pattern may become obscured. Brown widows are often preyed on by mud dauber
s and sometimes by digger wasp
s.
Brown widows can be located by finding their eggsacks, which are easily identifiable. They resemble a sandspur, having pointed projections all over, and they are sometimes described as "spiky" in appearance. Eggs hatch in approximately 20 days.
Like all Latrodectus species, L. geometricus has a neurotoxic venom that, drop by drop, is as toxic as the black widow's. Dr. G.B. Edwards, a University of Florida
arachnologist, claims brown widow venom is twice as potent as black widow venom, but is usually confined to the bite area and surrounding tissue, as opposed to the black widow's. A UC Riverside professor stated toxicity isn't the only factor. After viewing spider bites, he claimed the majority of spider bites were similar to those of other house spiders, possibly because they cannot deliver the same amount of venom as the black widow. Other sources say the brown widow is less venomous than L. mactans. Regardless, very few people who have been bitten describe the experience as painful. Unless a person is allergic or has a pre-existing medical condition, no concern is needed in the garden, home, or shed.
Similar widows include the L. rhodesiensis, a brown-colored relative of L. geometricus which is native to Zimbabwe
; both species are collectively known as brown button spiders throughout southern Africa
.
Southeastern United States
The Southeastern United States, colloquially referred to as the Southeast, is the eastern portion of the Southern United States. It is one of the most populous regions in the United States of America....
, southern
Southern United States
The Southern United States—commonly referred to as the American South, Dixie, or simply the South—constitutes a large distinctive area in the southeastern and south-central United States...
and southwestern
Southwestern United States
The Southwestern United States is a region defined in different ways by different sources. Broad definitions include nearly a quarter of the United States, including Arizona, California, Colorado, Nevada, New Mexico, Oklahoma, Texas and Utah...
United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
(including Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
, Alabama
Alabama
Alabama is a state located in the southeastern region of the United States. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, and Mississippi to the west. Alabama ranks 30th in total land area and ranks second in the size of its inland...
, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, Kansas
Kansas
Kansas is a US state located in the Midwestern United States. It is named after the Kansas River which flows through it, which in turn was named after the Kansa Native American tribe, which inhabited the area. The tribe's name is often said to mean "people of the wind" or "people of the south...
, Oklahoma, Nevada
Nevada
Nevada is a state in the western, mountain west, and southwestern regions of the United States. With an area of and a population of about 2.7 million, it is the 7th-largest and 35th-most populous state. Over two-thirds of Nevada's people live in the Las Vegas metropolitan area, which contains its...
, Louisiana
Louisiana
Louisiana is a state located in the southern region of the United States of America. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state in the U.S. with political subdivisions termed parishes, which are local governments equivalent to counties...
, Mississippi
Mississippi
Mississippi is a U.S. state located in the Southern United States. Jackson is the state capital and largest city. The name of the state derives from the Mississippi River, which flows along its western boundary, whose name comes from the Ojibwe word misi-ziibi...
, Georgia
Georgia (U.S. state)
Georgia is a state located in the southeastern United States. It was established in 1732, the last of the original Thirteen Colonies. The state is named after King George II of Great Britain. Georgia was the fourth state to ratify the United States Constitution, on January 2, 1788...
, South Carolina, North Carolina, Tennessee
Tennessee
Tennessee is a U.S. state located in the Southeastern United States. It has a population of 6,346,105, making it the nation's 17th-largest state by population, and covers , making it the 36th-largest by total land area...
, Ohio
Ohio
Ohio is a Midwestern state in the United States. The 34th largest state by area in the U.S.,it is the 7th‑most populous with over 11.5 million residents, containing several major American cities and seven metropolitan areas with populations of 500,000 or more.The state's capital is Columbus...
, Michigan
Michigan
Michigan is a U.S. state located in the Great Lakes Region of the United States of America. The name Michigan is the French form of the Ojibwa word mishigamaa, meaning "large water" or "large lake"....
, Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
, New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...
and Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
); outside of the U.S. there are reports in parts of Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, Afghanistan
Afghanistan
Afghanistan , officially the Islamic Republic of Afghanistan, is a landlocked country located in the centre of Asia, forming South Asia, Central Asia and the Middle East. With a population of about 29 million, it has an area of , making it the 42nd most populous and 41st largest nation in the world...
, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
and Cyprus
Cyprus
Cyprus , officially the Republic of Cyprus , is a Eurasian island country, member of the European Union, in the Eastern Mediterranean, east of Greece, south of Turkey, west of Syria and north of Egypt. It is the third largest island in the Mediterranean Sea.The earliest known human activity on the...
. The origin of this species is uncertain, as specimens were independently discovered in both Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
and the Americas
Americas
The Americas, or America , are lands in the Western hemisphere, also known as the New World. In English, the plural form the Americas is often used to refer to the landmasses of North America and South America with their associated islands and regions, while the singular form America is primarily...
. They are usually found around buildings in tropical areas.
L. geometricus is generally lighter in color than the black widow
Black widow spider
Latrodectus mactans, the Southern black widow, is a highly venomous species of spider in the genus Latrodectus. They are well known for the distinctive black and red coloring of the female of the species and for the fact that she will occasionally eat her mate after reproduction. The species is...
species—the color can range from tan to dark brown to black, with shades of grey also possible. Like the black widow species in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, L. geometricus has a prominent "hourglass" marking on the underside of the abdomen; the brown widow's hourglass, however, is usually a vivid orange or a yellowish color. Unlike the black widow, L. geometricus has a black-and-white "geometric" pattern on the dorsal side of its abdomen. Although the Latin name comes from this pattern, a spider's coloring can and does darken over time and the pattern may become obscured. Brown widows are often preyed on by mud dauber
Mud dauber
Mud dauber is a name commonly applied to a number of wasps from either the family Sphecidae or Crabronidae that build their nests from mud...
s and sometimes by digger wasp
Digger wasp
Wasps of the genus Sphex are cosmopolitan predators of the family Sphecidae that sting and paralyze prey insects. There are over 130 known digger wasp species. In preparation for egg laying, they construct a protected "nest" and then stock it with captured insects...
s.
Like all Latrodectus species, L. geometricus has a neurotoxic venom that, drop by drop, is as toxic as the black widow's. Dr. G.B. Edwards, a University of Florida
University of Florida
The University of Florida is an American public land-grant, sea-grant, and space-grant research university located on a campus in Gainesville, Florida. The university traces its historical origins to 1853, and has operated continuously on its present Gainesville campus since September 1906...
arachnologist, claims brown widow venom is twice as potent as black widow venom, but is usually confined to the bite area and surrounding tissue, as opposed to the black widow's. A UC Riverside professor stated toxicity isn't the only factor. After viewing spider bites, he claimed the majority of spider bites were similar to those of other house spiders, possibly because they cannot deliver the same amount of venom as the black widow. Other sources say the brown widow is less venomous than L. mactans. Regardless, very few people who have been bitten describe the experience as painful. Unless a person is allergic or has a pre-existing medical condition, no concern is needed in the garden, home, or shed.
Zimbabwe
Zimbabwe is a landlocked country located in the southern part of the African continent, between the Zambezi and Limpopo rivers. It is bordered by South Africa to the south, Botswana to the southwest, Zambia and a tip of Namibia to the northwest and Mozambique to the east. Zimbabwe has three...
; both species are collectively known as brown button spiders throughout southern Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
.
External links
- Brown Widow Spiders article at University of Florida Extension, Sarasota
- Brown Widow Fact Sheet and photos from San Diego
- Sexual Cannibalism in the Brown Widow Spider (Latrodectus geometricus)
- Center for Invasive Species Research info on the Brown Widow Spider
- http://cisr.ucr.edu/brown_widow_spider.html