''Bruchidius villosus'' is a species of

bean weevil The bean weevils or seed beetles are a subfamily (Bruchinae) of beetles, now placed in the family Chrysomelidae, though they have historically been treated as a separate family. They are granivores, and typically infest various kinds of seeds ...

known by the common names broom seed beetle and Scotch broom bruchid. This beetle is used as an agent of

biological pest control Biological control or biocontrol is a method of controlling pests, such as insects, mites, weeds, and plant diseases, using other organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also invo ...

against the

noxious weed A noxious weed, harmful weed or injurious weed is a weed that has been designated by an agricultural or other governing authority as a plant that is injurious to agricultural or horticultural crops, natural habitats or ecosystems, or humans or liv ...

known as

Scotch broom ''Cytisus scoparius'' ( syn. ''Sarothamnus scoparius''), the common broom or Scotch broom, is a deciduous leguminous shrub native to western and central Europe. In Britain and Ireland, the standard name is broom; this name is also used for other ...

(''Cytisus scoparius''). This is a dark gray weevil about two millimeters long. The female lays about ten eggs on the seed pod of the plant. The

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

hatches from the egg at the point it is attached to the pod and burrows into the pod, where it develops and feeds on the seeds. The larva is one to two millimeters long and gelatinous white. It

pupa A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their ...

tes in the seed coat. When the seed pod ripens and splits open, adult weevils emerge. This beetle is native to Europe. It was introduced to the United States by accident but was found to drastically reduce seed production in Scotch broom, its host plant. It became one of the newest insects to be deliberately released for the control of the plant in the 1990s. Its viability as a biocontrol agent is under study. It is used less often in New Zealand because it was found to attack plants other than its target when introduced there.

References

* Coombs, E. M., et al., Eds. (2004). ''Biological Control of Invasive Plants in the United States''. Corvallis: Oregon State University Press, 162. * Sheppard, A., M. Haines & T. Thomann. (2006). Native-range research assists risk analysis for non-targets in weed biological control: the cautionary tale of the broom seed beetle. ''Aust J Entom'' 45:4 292–97. Bruchinae Insects used for control of invasive plants Biological pest control beetles Beetles of Europe Beetles described in 1792 Taxa named by Johan Christian Fabricius {{Bruchinae-stub