Cockchafer

They have white bodies that curve into an arc with a black coloration at the abdomen and long, hairy, and well developed legs.

Sexual dimorphism is observed as male beetles, at dusk, will begin to swarm and locate around groups of trees at forest edges.

[6] These swarms typically have minimal damage to the trees, but they are occasionally harmful in cherry or plum orchards because of their consumption of blossoms.

[6] Green leaf volatiles (GLVs) are a series of saturated and monounsaturated six-carbon aldehydes, alcohols, and esters released by vascular plants in response to stresses.

It will continue feeding on roots, particularly grasses, cereals, and other crops, during its three larval stages, only pausing to burrow deep into the soil for winter hibernation.

This structure is a thin layer of cells that covers a number of sensory units consisting of dendrite bundles.

They've also been found to push their heads into the walls of their burrows and probe with their antennae, likely to taste the soil with bristle-like sensilla.

In 1320, for instance, cockchafers were brought to court in Avignon and sentenced to withdraw within three days onto a specially designated area, otherwise they would be outlawed.

In the pre-industrialised era, the main mechanism to control their numbers was to collect and kill the adult beetles, thereby interrupting the cycle.

Cockchafer larvae can also be fried or cooked over open flames, although they require some preparation by soaking in vinegar in order to purge them of soil in their digestive tracts.

Combined with the transformation of many pastures into agricultural land, this has resulted in a decrease of the cockchafer to near-extinction in some areas in Europe in the 1970s.

Due to legal provisions from the European Union for the sustainable use of pesticides, aerial treatment, which had been used to successfully control M. melolontha populations, is now banned.

[18] Azadirachtin is a chemical that inhibits maturation feeding and egg development, but low persistence and difficulty spraying it high enough in trees prevents widespread use.

The unlikelihood of developing resistance due to the sex pheromones being produced by the beetles makes this a promising method of pest control.

[10] Entomopathogenic bacteria from the genera Steinernema and Heterorhabditis are also being investigated, but they have been difficult to apply to fields as opposed to laboratory settings.

[10] Poor results with the application of these methods have stemmed intensive research into the gut enzymes and microbiome of M. melolontha to determine if they are acting as defense against entomopathogenic organisms.

[19] The gut enzymes and microbiota of M. melolontha larvae allow them to exploit a variety of ecological niches unique to their phylogenetic family.

[19] Proteolytic activity of enzymes in the midgut is hypothesised to increase resistance to entomopathogenic bacteria in the beetle larvae.

[19] The hindgut has a high density of bacteria that ferment recalcitrant residues such as cellulose, with the byproducts being absorbed by the beetle.

[21] Some research on the M. melolontha microbiome has been focused on increasing the entomopathogenic properties of nematodes used as pest control due to their symbiosis.

The bacteria will release lytic enzymes and other antimicrobial substances to decrease competition from the beetle's native microbiome.

Bacterial species in the midgut of M. melolontha such as Pseudomonas chlororaphis have been found to fight back, acting as antagonists to entomopathogenic bacteria.

[20] Environmental factors such as temperature, humidity, and plant type have a considerable impact on the existence and behaviour of cockchafers in wooded environments.

It indicates that cockchafer populations are strongly influenced by climatic conditions, with warmer temperatures and higher humidity level favouring their occurrence.

Additionally, specific vegetation types, including deciduous trees and shrubs, provide suitable habitats for cockchafers, facilitating their survival and reproduction within forest stands.

[13] The name "cockchafer"[22] derives from the late-17th-century usage of "cock"[23] (in the sense of expressing size or vigour) + "chafer"[24] which simply means an insect of this type, referring to its propensity for gnawing and damaging plants.

As such, the name "cockchafer" can be understood to mean "large plant-gnawing beetle" and is applicable to its history as a pest animal.

In ancient Greece, boys caught the insect, tied a linen thread to its feet and set it free, amusing themselves to watch it fly in spirals.

[26] Cockchafers appear in the fairy tales "Thumbelina" by Hans Christian Andersen and "Princess Rosette" by Madame d'Aulnoy.

The verse dates back to the Thirty Years' War in the first half of the 17th century, in which Pomerania was pillaged and suffered heavily.

Close up of a male cockchafer, showing the seven "leaves" on the antennae
Female M. melolontha Beetle.
Male M. melolontha Beetle.
Larva (grub)
Max and Moritz shaking cockchafers from a tree
A group of cockchafers in Ukraine