Green click beetle

The green click beetle (lat. Cidnopus aeruginosus) is a member of the Elateridae family. Adult beetles typically measure 8–11 mm in length and are distinguished by a metallic green or bronze coloration.

The body is covered in fine hairs that create a distinctive metallic sheen. The larvae, commonly known as wireworms, possess a cylindrical, hard-bodied structure that allows them to navigate efficiently through the soil profile.

These insects undergo complete metamorphosis. A unique survival trait of the adults is their ability to "click" and spring into the air when flipped on their backs, a defensive mechanism to regain their footing.

Larvae remain in the soil for most of their 3 to 5-year development cycle, migrating vertically depending on soil moisture and temperature conditions throughout the seasons.

The species thrives in environments with moderate moisture and dense vegetation, making agricultural fields with poor weed management particularly susceptible to colonization.

The primary economic damage is caused by the larvae, which are voracious generalist feeders. They attack the subterranean parts of a vast range of cultivated crops and wild vegetation.

In cereal crops, wireworms feed on germinating seeds by hollowing out the embryo and also cut through the stems of young seedlings at the root node, causing sudden plant death and crop thinning.

Root vegetables, such as potatoes, carrots, and sugar beets, suffer significantly as larvae tunnel deep into the roots. This damage ruins the marketability of the produce and invites secondary rots.

Beyond physical destruction, the wounds left by larval feeding act as entry points for various soil-borne pathogens, including bacteria and fungi, which exacerbate the crop loss.

• Cereals (wheat, corn, barley).
• Root crops (potatoes, carrots, beets).
• Various ornamental and field-grown vegetables.

Adult beetles typically emerge in late spring, between May and June, coinciding with warmer soil temperatures and the onset of plant growth in the fields.

During the mating season, females deposit eggs in the soil, selecting areas with ample moisture and protective vegetative cover to ensure the survival of the neonate larvae.

The active feeding season for larvae spans the entire warm period of the year. During this time, they migrate within the soil profile to find fresh roots and germinating seeds.

As soil temperatures drop in the autumn, larvae move deeper into the soil horizon to escape frost and overwinter in a state of suspended activity until the following spring.

Successful monitoring requires tracking adult flights in the spring to predict future larval pressure, as the multi-year life cycle complicates immediate eradication efforts.

The first indicator of an infestation is the appearance of wilting or chlorotic plants in patches across the field. These affected plants can often be pulled up with very little resistance.

Closer inspection of the root system or the base of the stem often reveals clean-cut wounds or irregular tunneling caused by the feeding of the larvae.

In root crops, harvested vegetables may show small, deep, circular holes that extend into the flesh of the root, which is a definitive sign of wireworm activity.

Fields with a history of low-density grass or fallow periods are at higher risk. Finding adults in the early season indicates an established population that requires attention.

Soil sampling (digging pits or using bait traps) is the most reliable method for quantifying the population of larvae present in a specific field before planting.

Strategic crop rotation is the cornerstone of control. Avoiding susceptible crops immediately after grassy fields or pastures significantly reduces the immediate threat to the new planting.

Autumn plowing serves as an effective mechanical control method. It exposes larvae to cold temperatures and surface-feeding avian predators, significantly reducing their survival rate.

Diligent weed management is essential. Eliminating rhizomatous weeds, such as couch grass, deprives larvae of their alternative food sources between crop seasons.

Seed treatments with systemic insecticides are the most common and effective preventive measures for cereals, providing a protective zone around the seed during its most vulnerable stage.

In cases of severe infestation, granular soil-applied insecticides can be incorporated at the time of planting to protect the root zone throughout the critical growth period.