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The Curculionidae are a family of weevils, commonly called snout beetles or true weevils. They are one of the largest animal families with 6,800 genera and 83,000 species described worldwide. They are the sister group to the family Brentidae.
They include the bark beetles as the 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.
Adult Curculionidae can be recognised by the well-developed, downwards-curved snout (rostrum) possessed by many species, though the rostrum is sometimes short (e.g. Entiminae). They have elbowed antennae that end in clubs, and the first antennal segment often fits into a groove in the side of the rostrum. The body tends to be robust, convex, heavily sclerotised and covered in scales or bristles. Curculionidae range in size from 1–35 mm long, usually being 5–15 mm long. Most Curculionidae are sexually dimorphic with females (compared to males) having antennae positioned more basally and a longer, thinner rostrum.
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Larval Curculionidae are C-shaped and lightly sclerotised, with minute antennae, robust mandibles and no legs.
Most weevils feed on plants as larvae and adults, and they include important pests of cultivated plants that chew holes in fruits, nuts and other parts. The long rostrum possessed by most adult weevils is used by females to help lay eggs (oviposit) inside plant tissue. Some feed on rotten wood or bark (e.g. Cossoninae and Cryptorhynchinae), and some are wood-borers that feed on ambrosia fungi (Platypodinae and some Scolytinae).
Although pesticide resistance hasn't historically been an issue with these insects, recently a mutation was discovered in association with the voltage-gated sodium channel in the species Sitophilus zeamais, indicating there is a lot to learn about how these insects adapt to changing environments.
