There are over 50,000 weevil species worldwide, many of which are pests. Weevils are a highly successful group of beetles (the Curculionidae) characterised by their prominent snout (called a rostrum) with jaws at the tip. This family is represented by more than 400 species in Britain. They are easily identified by their elbowed antennae located halfway down the rostrum. Weevils are herbivores and often lay their eggs inside the host plant, where the larvae develop. Some species (e.g. Sitophilus species) are major pests of grain and other seeds worldwide. The economic loss resulting from weevil infestation is enormous, especially in developing countries. Attempts to control these pests with insecticides have often failed because the beetles, like other pest insects (e.g. mosquitoes, aphids), have evolved resistance to the toxic effects of the chemicals.
Boll weevils almost devestated the US cotton industry, which has only been saved by the use of huge amounts of insecticide.
The large larvae of the palm weevil Rhynchophorus phoenicis are a traditional food item in Angola.
The tiny weevil Cyrtobagous salviniae is responsible for saving communities in Papua New Guinea. It was introduced as a means of controlling the aquatic fern Salvinia, which can completely block waterways.