Hister quadrimaculatus (Linnaeus, 1758)
Family: Histeridae
The size of adults is usually 7 - 11 mm. The body is typically compact, stocky (shortly elliptical to rounded) and strongly dorsoventrally flattened. The elytra are shiny black with the characteristic four red or yellowish-red spots. These spots can be highly variable in shape and size, and in some forms are even completely absent. The elytra are truncate and do not cover the entire dorsum - typically the last two tergites are exposed, a characteristic feature of the family Histeridae. The head may be retracted into the prothorax (front of the thorax) so that it is not visible when viewed from above.
The antennae are short, knobbed and club-shaped. The legs are short, with flat and toothed fore tibiae, adapted for burrowing. When threatened, they retract the head and fold the legs under the body and "stiffen" (thanatosis), a typical behaviour of representatives of Histeridae.
The main active period for adults is in spring and summer - typically April to August. Adults are predominantly nocturnal (nocturnal), although they have been observed during the day during their frequent movements. The species is primarily coprophagous - thus found mainly in livestock faeces (cow dung, horse manure), but also under stones, in decaying organic matter (mainly where fly larvae are found) or in decaying vegetables in warm areas. The geographical distribution of the species covers western, southern (e.g. France, Corsica, Italy) and central Europe, as well as the Caucasus and Asia Minor. In the Czech Republic it is very local and rather rare. In terms of food requirements, it is a typical predator whose food consists mainly of larvae, eggs and pupae of flies, soft-bodied larvae of other insects and in some cases also adult insects. Some individuals of the family Histeridae may cannibalize other species of the family Histeridae. The beetles locate droppings and carcasses by smell. They do not consume droppings or carcasses themselves, feeding mainly on the larvae of flies that are found there.
The evolution of the species is relatively rapid. The total development time (from egg to adult) takes an average of 21 days at 30°C. The female lays her eggs in decaying organic matter (droppings, carcasses) where the larvae will have plenty of food. Hatching of the larva takes on average 4 days. After hatching, the larvae begin to actively feed on eggs and fly larvae. Carrion beetles have only two larval instars, which is quite unusual for beetles. Hatching takes about 1 week on average at optimum temperatures. They normally have one generation per year, but in some warmer areas they may have two generations per year. Adult beetles live on average 2 to 3 years.
Both beetles and larvae play an important role in forensic entomology in determining the time of death.
Picture Source: Schmidt, 2019
