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A weevil is any beetle
Beetle

Beetles are the group of insects with the largest number of known species. They are placed in the order Coleoptera , which contains more described species than in any other order in the animal, constituting about 25% of all known life-forms....
 from the Curculionidae superfamily. They are usually small, less than 6 mm (¼ inch), and herbivorous
Herbivore

Herbivory is a form of predation in which an organism, known as an herbivore, heterotrophs principally autotrophs such as plants, algae and photosynthesizing bacteria....
. Due to the shape of their heads, weevils are commonly known as snout beetles. There are over 60,000 species in several families, mostly in the family Curculionidae
Curculionidae

Curculionidae is the family of the "true" weevils . With over 60,000 species described worldwide, it is the largest of the beetle families.They are recognized by their distinctive long snout and geniculate antennae with small clubs; beyond that curculionids have considerable diversity of form and size, with adult lengths ranging from 1&nbs...
 (the true weevils). Some other beetles, although not closely related, bear the name "weevil", such as the biscuit weevil
Drugstore beetle

The Drugstore beetle is a tiny, brown beetle that can be found infesting a wide variety of products, and is among the most common non-weevils to be found there....
 (Stegobium paniceum), which belongs to the family Anobiidae
Anobiidae

Anobiidae is a family of beetles. The larvae of a number of species bore into wood, earning the name "woodworm" or "wood borer". A few species are pests, causing damage to wooden furniture and house structures, notably the death watch beetle, Xestobium rufovillosum, and the common furniture beetle, Anobium punctatum....
.

Many weevils are damaging to crops.






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Encyclopedia


A weevil is any beetle
Beetle

Beetles are the group of insects with the largest number of known species. They are placed in the order Coleoptera , which contains more described species than in any other order in the animal, constituting about 25% of all known life-forms....
 from the Curculionidae superfamily. They are usually small, less than 6 mm (¼ inch), and herbivorous
Herbivore

Herbivory is a form of predation in which an organism, known as an herbivore, heterotrophs principally autotrophs such as plants, algae and photosynthesizing bacteria....
. Due to the shape of their heads, weevils are commonly known as snout beetles. There are over 60,000 species in several families, mostly in the family Curculionidae
Curculionidae

Curculionidae is the family of the "true" weevils . With over 60,000 species described worldwide, it is the largest of the beetle families.They are recognized by their distinctive long snout and geniculate antennae with small clubs; beyond that curculionids have considerable diversity of form and size, with adult lengths ranging from 1&nbs...
 (the true weevils). Some other beetles, although not closely related, bear the name "weevil", such as the biscuit weevil
Drugstore beetle

The Drugstore beetle is a tiny, brown beetle that can be found infesting a wide variety of products, and is among the most common non-weevils to be found there....
 (Stegobium paniceum), which belongs to the family Anobiidae
Anobiidae

Anobiidae is a family of beetles. The larvae of a number of species bore into wood, earning the name "woodworm" or "wood borer". A few species are pests, causing damage to wooden furniture and house structures, notably the death watch beetle, Xestobium rufovillosum, and the common furniture beetle, Anobium punctatum....
.

Many weevils are damaging to crops. The grain or wheat weevil
Wheat weevil

Wheat weevils occur all over the world and are a common pest in many places. They can cause significant damage to harvested grains that are being stored and may drastically decrease yields....
 (Sitophilus granarius) damages stored grain
Cereal

Cereals, or cereal grains, are mostly Poaceae cultivated for their edible brans or fruit seeds . Cereal grains are grown in greater quantities and provide more energy worldwide than any other type of crop; they are therefore staple foods....
. The boll weevil
Boll weevil

The boll weevil is a beetle measuring an average length of six millimeters, which feeds on cotton buds and flowers. Thought to be native to Central America, it migrated into the US from Mexico in the late 19th century and had infested all US cotton-growing areas by the 1920s, devastating the industry and the people working in the American so...
 (Anthonomus grandis) attacks cotton
Cotton

Cotton is a soft, staple fiber that grows in a form known as a boll around the seeds of the cotton plant a shrub native to tropical and subtropical regions around the world, including the Americas, India and Africa....
 crops. It lays its eggs inside unripe cotton bolls, and the young weevils eat their way out.

Weevils are often found in dry foods including nuts and seeds, cereal and grain products. In the domestic setting, they are most likely to be observed when a bag of flour is opened, although they will happily infest most types of grain including oats, barley and breakfast cereals. Their presence is often indicated by the granules of the infested item sticking together in strings, as if caught in a cobweb. If ingested, E. coli
Escherichia coli

'Escherichia coli' , is a Gram negative bacterium that is commonly found in the lower gastrointestinal tract of warm-blooded animals. Most E....
 infection and other various diseases can be contracted from weevils, depending on their diet.

Taxonomy

Because there are so many species and such diversity, the higher classification of weevils is in a state of flux. Weevils are generally divided into two major divisions, the Orthoceri or primitive weevils, and the Gonatoceri or true weevils (Curculionidae
Curculionidae

Curculionidae is the family of the "true" weevils . With over 60,000 species described worldwide, it is the largest of the beetle families.They are recognized by their distinctive long snout and geniculate antennae with small clubs; beyond that curculionids have considerable diversity of form and size, with adult lengths ranging from 1&nbs...
). E. C. Zimmerman
Elwood Zimmerman

Elwood Curtin Zimmerman was an American entomologist best known for his two multivolume series: Insects of Hawaii published by the University of Hawaii Press and Australian Weevils published by Australia's CSIRO....
 proposed a third division, the Heteromorphi, for several intermediate forms . Primitive weevils are distinguished by having straight antennae, while true weevils have elbowed (geniculate) antennae. The elbow occurs at the end of the scape
Antenna (biology)

Antennae are paired appendages connected to the front-most morphogenesis of arthropods. In crustaceans, they are biramous and present on the first two segments of the head, with the smaller pair known as antennules....
 (first antennal segment) in true weevils, and the scape is usually much longer than the other antennal segments. Some exceptions occur. Nanophyini are primitive weevils (with very long trochanters
Arthropod leg

The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments are of Latin origin, and may be confused with terms for bones: coxa , trochanter , femur, tibia, tarsus , ischium, metatarsus, carpus, dactylus , patella....
) but have long scapes and geniculate antennae. From the true weevils, Gonipterinae
Gonipterinae

Gonipterinae is a subfamily of weevils. The larvae and adults are usually found on eucalyptus trees, where they feed upon the foliage. The larvae are legless and slug-like in appearance....
 and Ramphus have short scapes and little or no elbow.

The most recent classification system to family level was provided by Kuschel , with updates from Marvaldi et al. , and was achieved using phylogenetic analyses. The accepted families are the primitive weevils, Anthribidae, Attelabidae, Belidae, Brentidae, Caridae and Nemonychidae, and the true weevils Curculionidae. Most other weevil families were demoted to subfamilies or tribes. Weevil species radiation was shown to follow steps in plant evolution upon which the weevils feed.

Some of the features used to distinguish weevil families are:

Labrum visible as separate segment to clypeus Anthribidae, Nemonychidae
Antennae elbowed most Curculionidae, Nanophyini of Apioninae
Trochanters (segment between coxae and femora) as long or longer than coxae Apioninae including Nanophyini
Fore tibia with comb of setae in apical groove opposite tarsal articulation Belidae
Elytra striate (with longitudinal ridges or grooves) Brentidae, Curculionidae, Rhinorhynchinae
Rostrum short and broad Anthribidae, some Curculionidae (some Brachycerinae including Ithycerus (New York weevil
New York weevil

The New York weevil is an species of primitive weevil; large for weevils , it is covered with fine bristles and has a regular pattern of light and dark spots....
), Scolytinae and Platypodinae).
Maxillary palps long and projecting (visible from above at tip of rostrum) Anthribidae, Nemonychidae
Abdominal tergites 6 and 7 without spiracles Caridae
Gular suture (on ventral part of head) single not double Attelabidae, Brentidae, Curculionidae.


Phylogeny

A phylogeny of the Curculionidae based on 18S ribosomal DNA
Ribosomal DNA

Ribosomal DNA are sequences encoding RRNA. These sequences regulate amplification and Transcription_ initiation and contain transcribed and nontranscribed spacer segments....
 and morphological data is suggested below:

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