About Bruchidius villosus (Fabricius, 1792)
Bruchidius villosus (Fabricius, 1792) is a species of bean weevil with the common names broom seed beetle and Scotch broom bruchid. This beetle is used as a biological pest control agent against the noxious weed Scotch broom (Cytisus scoparius).
This is a dark gray weevil that grows to about two millimeters in length. The female lays approximately ten eggs on the seed pod of the Scotch broom plant. When the larva hatches from its egg, it hatches at the point where the egg is attached to the pod, then burrows into the pod. There, the larva develops and feeds on the plant's seeds. The larva measures one to two millimeters long, and is gelatinous white in color. It pupates inside the seed coat. Adult weevils emerge once the seed pod ripens and splits open.
This beetle is native to Europe. It was accidentally introduced to the United States, where it was discovered to drastically reduce seed production in its host plant, Scotch broom. It became one of the newest insects deliberately released for Scotch broom control in the 1990s. Its viability as a biocontrol agent remains under study. It is used less often in New Zealand, because after introduction it was found to attack plants other than its intended target Scotch broom.
