The rove beetles are a large
family (Staphylinidae) of beetles, primarily distinguished by their short elytra that leave more than half of their abdomens exposed.
With over 46,000 species in thousands of genera, the group is the second largest family of beetles after the Curculionidae (the true weevils). It is an ancient group, with fossil rove beetles known from the Triassic, 200 million years ago.
As might be expected for such a large family, there is considerable variation among the species. Sizes range from 1 to 35 mm (1.5 inches), with most in the 2–8 mm range, and the form is generally elongate, with some rove beetles being ovoid in shape. Colors range from yellow to reddish-brown to brown to black. The antennae are usually 11 segmented and filiform, with moderate clubbing in some genera. The abdomen may be very long and flexible, and some types of rove beetles superficially resemble earwigs.
Although rove beetles' appetites for other insects would seem to make them obvious candidates for biological control of pests, and empirically they are believed to be important controls in the wild, experiments with using them have not been notably successful. Greater success is seen with those species (genus Aleochara) that are parasitoids.
Rove beetles of the genus Stenus are very interesting insects. They are
specialist predators of small invertebrates such as collembola. Their labium can shoot out from the head using blood pressure. The thin rod of the labium ends in a pad of bristly hairs and hooks and between these hairs are small pores that exude an adhesive glue-like substance, which sticks to prey.