Mainly encountered on the chalk downlands of southern England, the beetle Drilus flaverscens is a prime example of sexual dimorphism, with the appearance and lifestyle of the males and females being very different.
The male looks like a typical adult beetle: it has wings, it can fly, and it may be found on flowers and foliage feeding on nectar, pollen, fruit and other plant material. The adult female insect, however, has a larval appearance; it is wingless, and it lives on the ground searching for snails which it kills with poisonous bites. Secreted digestive enzymes render the snail’s flesh into a liquid which is ingested.
When ready to mate, the female releases airborne pheromones which are detected by the male using its large comb-like antennae. Following mating, the female lays her eggs in the soil. After hatching, the emerging larvae are predatory on snails – feeding on them in a similar way to the adult female; this stage of their development may last for several years but, once reaching its maximum size, a larva overwinters in an empty snail shell. Within this protective environment, most of its hairs are lost and it enters into a resting, ‘pseudopupa’, state. It eventually becomes a true pupa before emerging as an adult beetle in the following spring.
