Curculionidae

The Curculionidae comprise the family of the "true" weevils (or "snout beetles"). It is the third-largest animal family, with over 40,000 species described worldwide. It is surpassed only by the Ichneumonidae (Hymenoptera), with over 60,000 species, and the Staphylinidae (Coleoptera), with 58,000 species.

It also includes the bark beetles as subfamily Scolytinae, which are modified in shape in accordance with their wood-boring lifestyle. They do not much resemble other weevils, so they were traditionally considered a distinct family, Scolytidae. The family also includes the ambrosia beetles, of which the present-day subfamily Platypodinae was formerly considered the distinct family Platypodidae.

Description

They are recognized by their distinctive long snouts and geniculate antennae with small clubs; beyond that, curculionids have considerable diversity of form and size, with adult lengths ranging from 1 to 40 mm (0.04 to 1.57 in).

Weevils are almost entirely plant feeders, and most species are associated with a narrow range of hosts, in many cases only living on a single species. With so many species to classify and over 400 genera, the taxonomy of this family is quite complicated, and authors disagree on the number and placement of various subfamilies, tribes, and subtribes.

Weevil

A weevil is a type of beetle from the Curculionoidea superfamily. They are usually small, less than 6 mm (0.24 in), and herbivorous. Over 60,000 species are in several families, mostly in the family Curculionidae (the true weevils). Some other beetles, although not closely related, bear the name "weevil", such as the biscuit weevil (Stegobium paniceum), which belongs to the family Anobiidae.

Many weevils are damaging to crops. The grain or wheat weevil (Sitophilus granarius) damages stored grain. The boll weevil (Anthonomus grandis) attacks cotton crops. It lays its eggs inside cotton bolls, and the larvae eat their way out.

One species of weevil, Austroplatypus incompertus, exhibits eusociality, one of the few organisms outside the Hymenoptera to do so.

Taxonomy

Because so many species exist in such diversity, the higher classification of weevils is in a state of flux. They are generally divided into two major divisions, the Orthoceri or primitive weevils, and the Gonatoceri or true weevils (Curculionidae). E. C. Zimmerman 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 (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), but have long scapes and geniculate antennae. From the true weevils, Gonipterinae and Ramphus have short scapes and little or no elbow.