Melolontha melolontha
common European cockchafer
(Also: maybug)

Also known as the June bug or May bug, the common cockchafer is found throughout temperate Europe and the continental United States. (Arnett, 1985; Fraval, 1998)

Common cockchafers typically live in areas with soft, shaded soil. The cockchafer is frequently found on agricultural land. (Fraval, 1998)

Adult cockchafers typically range from 25 to 30mm. Adult Melolontha melolontha have a dark head with a shiny black pronotum covered by short, closely set hairs. They also have a dull black abdomen and a long, flat pygidium. Eyes are multifaceted, with 5,475 facets per eye, providing very acute vision. Males have longer antennae than females, with a large, fan-like club protruding from each terminus. New wing cases are typically mottled with a white powder. Immature (larval) common cockchafers reach lengths of about 40 to 46mm, and have a dull white body colored black at the abdomenal extremity. Cockchafer grubs curve into an arc and have a large head with strong, grabbing mandibles. In overall appearance grubs are fleshy, elongated, and slightly hairy. (Burton, 1979; Fraval, 1998; Pesson, 1959)

Early larval development takes approximately 4 to 6 weeks. Larvae slow development over the winter, and in mid-April they suddenly spring back to activity and eat until October. They then hibernate until the third year, when they resume feeding in July and become fully mature in August. However, the fully mature adults do not become active until the following spring, giving the cockchafer a lengthy life cycle. (Blum, 1985; Fraval, 1998)

The reproductive cycle of the cockchafer is lengthy and triggered by a combination of hormones and environment. Environmental factors, such as the time of day and season trigger endocrines in females. Females in turn send out powerful pheromones, which males detect with their large antennae. Mating occurs typically in late May and early June. Females deposit eggs in a path opposite to that of the pre-mating flight. (Blum, 1985; Fraval, 1998)

After copulation, eggs are deposited about 20 at a time in soft soil. (Blum, 1985; Fraval, 1998)

Cockchafers' buzzing and squeaking around trees at dusk, and around lights at night are a common sound and sight on spring nights. Some cockchafers infest a single tree while others fly around an entire forest roaming for food. They can be often be found buzzing around house lights. (Burton, 1979; Fraval, 1998)

In April and May, adult cockchafers fly singly in search of food. Melolontha melolontha ear deciduous tree and fruit tree leaves, particularly oaks, maple, sweet chestnut, beech, plum, and walnut trees. While adults are considered harmful only in large populations, the eating habits of larvae cause far more damage to crops. Larvae gnaw at small roots of field plants, and are indiscriminate feeders; they eat grain, grass, tree, and beet roots, moving as much as 30 cm a day while eating large sections of crop rootlets. Cockchafer larvae feed on new, fresh soil roots and do not usually eat decaying organic matter. (Fraval, 1998)

No positive human benefit has yet been attributed to the common cockchafer.

Adults generally only cause damage when they are found in extremely large populations. Larvae, however, are reviled in gardens and farms everywhere they inhabit. This is because the larvae gorge themselves for over 3 years on the fresh rootlets of plants and trees. This can wipe out crops and weaken older trees. (Fraval, 1998)

This animal requires no special status.

Juvenile larvae feed on parental excrement in order to ingest a certain symbiotic intestinal bacteria. The bacteria then live within the larval gut and help digest cellulose fibers from rootlets. (Arnett, 1985; Fraval, 1998)