Predator Avoidance Strategy of the European Click Beetle

Pascal Schneider from Mainz, central Germany recorded this interesting predator avoidance behavior on the night of May 23rd 2012. He heard a curious clicking sound coming from a corner of terrace next to his kitchen. He quickly realized that a Pholcid spider was attacking a beetle and didn’t hesitate to record the event.

The beetle Athous haemorrhoidalis (Elateridae family) is species strictly found in europe. As in most insects, females are always larger than males. Larvae develop in soil and feed on the roots of various wide range of plants and can be a pest in agricultural fields. Larvae may also show predatory activity and can feed on winter moth. The larval stage lasts at least two years, followed by pupation in June or July. Eclosure takes place immediately after in August. The imago overwinters in the pupal case underground, subsequently emerging in May or June of the following year. Imago insects can be readily found resting on flowers of various species (particularly Apiaceae). Imagos are floricole and eat pollen.

A. harmorrhoidalis is a pollinator of the Orchid Coeloglossum viride L. (frog orchid). Birds, such as tits, are the main predator of this species. It is one of the most important prey items for Ficedula albicollis (collared flycatcher). A. haemorrhoidalis is a lowland species not observed above 600 m elevation. In Great-Britain, this species is known from Holocene (-10000 years) records, i.e. just after the last glacial age and is reported to hybridize with hybridize with A. vittatus.

Athous haemorrhoidalis, is commonly known as Click Beetle which is an extremely apt name. The beetle can flick itself upright if it falls backwards by flexing a well developed joint between the first and second thoracic sternites. As the main video demonstrates this is an effective defense mechanism. Most click beetles also drop themselves into the grass if you don’t approach carefully. Most Click Beetles are dull brown in color, but a few do posess a metallic sheen and some are even red. If you are into click beetles you can watch a different species ovipositing.