Weevils are beetles belonging to the superfamily Curculionoidea, known for their elongated snouts. They are usually small – less than 6 mm in length – and herbivorous. Approximately 97,000 species of weevils are known. They belong to several families, with most of them in the family Curculionidae. It also includes bark beetles, which while morphologically dissimilar to other weevils in lacking the distinctive snout, is a subfamily of Curculionidae. Some other beetles, although not closely related, bear the name "weevil", such as the biscuit weevil, which belongs to the family Ptinidae.
Ambrosia beetles are beetles of the weevil subfamilies Scolytinae and Platypodinae, which live in nutritional symbiosis with ambrosia fungi. The beetles excavate tunnels in dead or stressed trees in which they cultivate fungal gardens, their sole source of nutrition. After landing on a suitable tree, an ambrosia beetle excavates a tunnel in which it releases its fungal symbiont. The fungus penetrates the plant's xylem tissue, extracts nutrients from it, and concentrates the nutrients on and near the surface of the beetle gallery. Ambrosia fungi are typically poor wood degraders, and instead utilize less demanding nutrients. Symbiotic fungi produce and detoxify ethanol, which is an attractant for ambrosia beetles and likely prevents growth of antagonistic pathogens and selects for other beneficial symbionts. The majority of ambrosia beetles colonize xylem of recently dead trees, but some attack stressed trees that are still alive, and a few species attack healthy trees. Species differ in their preference for different parts of trees, different stages of deterioration, and in the shape of their tunnels ("galleries"). However, the majority of ambrosia beetles are not specialized to any taxonomic group of hosts, unlike most phytophagous organisms including the closely related bark beetles. One species of ambrosia beetle, Austroplatypus incompertus exhibits eusociality, one of the few organisms outside of Hymenoptera and Isoptera to do so.
A woodworm is the wood-eating larva of many species of beetle. It is also a generic description given to the infestation of a wooden item by these larvae.
A bark beetle is the common name for the subfamily of beetles Scolytinae. Previously, this was considered a distinct family (Scolytidae), but is now understood to be a specialized clade of the "true weevil" family (Curculionidae). Although the term "bark beetle" refers to the fact that many species feed in the inner bark (phloem) layer of trees, the subfamily also has many species with other lifestyles, including some that bore into wood, feed in fruit and seeds, or tunnel into herbaceous plants. Well-known species are members of the type genus Scolytus, namely the European elm bark beetle S. multistriatus and the large elm bark beetle S. scolytus, which like the American elm bark beetle Hylurgopinus rufipes, transmit Dutch elm disease fungi (Ophiostoma). The mountain pine beetle Dendroctonus ponderosae, southern pine beetle Dendroctonus frontalis, and their near relatives are major pests of conifer forests in North America. A similarly aggressive species in Europe is the spruce ips Ips typographus. A tiny bark beetle, the coffee berry borer, Hypothenemus hampei is a major pest on coffee plantations around the world.
The beetle subfamily Curculioninae is part of the weevil family Curculionidae. It contains over 23,500 described species in 2,200 genera, and is therefore the largest weevil subfamily. Given that the beetle order (Coleoptera) contains about one-quarter of all known organisms, the Curculioninae represent one of the – if not the – most successful radiations of terrestrial Metazoa.
Belidae is a family of weevils, called belids or primitive weevils because they have straight antennae, unlike the "true weevils" or Curculionidae which have geniculate (elbowed) antennae. They are sometimes known as "cycad weevils", but this properly refers to a few species from the genera Parallocorynus and Rhopalotria.
The term mycangium is used in biology for special structures on the body of an animal that are adapted for the transport of symbiotic fungi. This is seen in many xylophagous insects, which apparently derive much of their nutrition from the digestion of various fungi that are growing amidst the wood fibers. In some cases, as in ambrosia beetles, the fungi are the sole food, and the excavations in the wood are simply to make a suitable microenvironment for the fungus to grow. In other cases, wood tissue is the main food, and fungi weaken the defense response from the host plant.
Brentidae, sometimes known as the primitive weevils, is a cosmopolitan family of primarily xylophagous beetles also known as straight-snouted weevils. The concept of this family has been expanded with the inclusion of three groups formerly placed in the Curculionidae; the subfamilies Apioninae, Cyladinae, and Nanophyinae, as well as the Ithycerinae, previously considered a separate family. They are most diverse in the tropics, but occur throughout the temperate regions of the world. They are among the families of weevils that have non-elbowed antennae, and tend to be elongate and flattened, though there are numerous exceptions.
Cryptorhynchinae is a large subfamily of weevils (Curculionidae), with some 6000 species. They are found in most zoogeographic regions although they are most diverse in the Neotropics, Australia and Oceania.
Eobelinae are an extinct weevil subfamily that throve in the late Mesozoic. They belong to the family Nemonychidae. The Eobelidae were widespread, occurring at least in Central Asia, Spain and Brazil during the Late Jurassic and Early Cretaceous.
Oxycoryninae are subfamily of primitive weevils of the family Belidae, but sometimes treated as a distinct family Oxycorynidae. Like in other belids, their antennae are straight, not elbowed as in the true weevils (Curculionidae), and their larvae feed on the wood of diseased or dying plants or on deadwood or fruits; they tend to avoid healthy plants.
The Entiminae are a large subfamily in the weevil family Curculionidae, containing most of the short-nosed weevils, including such genera as Entimus, Otiorhynchus, Phyllobius, Sitona, and Pachyrrhynchus. In comparison with their stunning diversity, only a few of these weevils are notorious pests of major economic importance. Entimines are commonly encountered in the field, including urban environments, and abundant in entomological collections.
Baridinae is a subfamily of true weevils (Curculionidae). It was established by Carl Johan Schönherr in 1836. Some 4,300 species in 550 genera are placed here, most of which occur in the New World. A few are economically significant pests, while others are in turn used for biocontrol of invasive plant pests. This subfamily also contains a few endangered species.
The maize weevil, known in the United States as the greater rice weevil, is a species of beetle in the family Curculionidae. It can be found in numerous tropical areas around the world, and in the United States, and is a major pest of maize. This species attacks both standing crops and stored cereal products, including wheat, rice, sorghum, oats, barley, rye, buckwheat, peas, and cottonseed. The maize weevil also infests other types of stored, processed cereal products such as pasta, cassava, and various coarse, milled grains. It has even been known to attack fruit while in storage, such as apples.
Platypodinae is a weevil subfamily in the family Curculionidae. They are important early decomposers of dead woody plant material in wet tropics; all but two species are ambrosia beetles that cultivate fungi in tunnels excavated in dead wood as the sole food for their larvae. They are sometimes known as pinhole borers.
The European spruce bark beetle, is a species of beetle in the weevil subfamily Scolytinae, the bark beetles, and is found from Europe to Asia Minor and some parts of Africa.
Ectemnorhinini is a weevil tribe in the subfamily Entiminae.
Xylosandrus crassiusculus, known generally as the Asian ambrosia beetle or granulate ambrosia beetle, is a species of tropical bark beetle in the family Curculionidae. It is native to Asia and has spread to Africa, Europe, Australasia and the Americas. The adult beetle is reddish-brown and some 2 to 3 mm long.
Crossotarsus saundersi, commonly known as stem borer, is a species of weevil found in Sri Lanka, Australia and New Zealand.
Euwallacea interjectus, is a species of weevil native to Asia but introduced to Westerns parts of the world.
