Click beetles, known for their distinctive clicking mechanism that allows them to right themselves when flipped over, are a common insect in the UK. This group of beetles, which includes around 73 species in Britain, is widespread across the country. These beetles are often seen in homes, gardens, and wooded areas. This article explores how to identify click beetles, avoid infestations, control them, and where they are typically found in the UK.
Identification of Click Beetles
Click beetles in the UK are generally brown or black and range in size from 1.5 to 21 mm, depending on the species. They have elongated bodies and can often be found resting on foliage, logs, and the bark of trees. The adult beetles possess a unique body mechanism that allows them to “click” and jump into the air when threatened or turned upside down. This is due to a spine on the prosternum, which fits into a cavity on the mesosternum, triggering the clicking movement.
In the UK, common species like Athous haemorrhoidalis and Agriotes pallidulus are typically found on grasses and roadside verges from spring through early summer. These species are identifiable by their brown coloration and frequent presence on umbellifer flowers. Other species, such as Stenagostus rhombeus, can grow up to 21 mm and are found in wooded areas, often active in the evening.
Wireworms, the larvae of click beetles, are cylindrical, pale to tan grubs that can be up to 30 mm long. They have a hard, shiny body with three pairs of legs near the head. These larvae are commonly found underground, where they feed on the roots of plants and can cause significant damage to crops and garden plants.
How to Avoid Click Beetles
Click beetles are often attracted to homes and gardens by artificial lights, especially during warm spring and summer nights. To reduce the likelihood of an infestation, consider reducing the use of bright outdoor lights or switching to lower-intensity, motion-activated lighting. Proper maintenance of doors and windows, including using screens without holes and ensuring tight seals, can also prevent beetles from entering your home.
In gardens, maintaining healthy soil and removing plant debris can discourage click beetles from laying eggs in the area. These beetles prefer moist environments, so ensuring proper drainage and avoiding overwatering can help reduce their presence.
How to Control Click Beetles and Wireworms
The most problematic stage of the click beetle life cycle is the wireworm stage, where the larvae can cause significant damage to crops such as potatoes, beets, cereals, and vegetables by feeding on plant roots. Controlling wireworms can be challenging due to their underground habits and long life cycle, which can last up to five years.
Effective control methods include:
- Crop Rotation: Rotating crops regularly can disrupt the life cycle of wireworms, reducing their numbers in the soil.
- Deep Ploughing: Tilling the soil deeply can expose wireworms to the surface, where they are more vulnerable to predators and environmental conditions.
- Insecticides: Applying insecticides to the soil can target wireworms, though they are known for their ability to recover from exposure to insecticides over time.
- Baiting: Setting traps with poison-baited plants or using pheromone traps can help reduce adult click beetle populations.
For homes and buildings, adult beetles that enter can be controlled using vacuum cleaners or aerosol insecticides. Reducing outdoor lighting, sealing cracks in foundations, and ensuring windows and doors are well-maintained will also help keep them from entering homes.
Where Click Beetles Live in the UK
Click beetles are found throughout the UK, from gardens and farmlands to wooded areas. Many species thrive in temperate regions with moist soil, particularly in environments that support the development of their larvae. Some species, such as Actenicerus sjaelandicus, are associated with wetland habitats, while others prefer grasslands, meadows, and agricultural lands.
In urban areas, click beetles may enter homes, especially during late spring and summer when they are most active. These beetles are attracted to light and can become a nuisance indoors, although they do not pose any direct threat to humans.
Life Cycle of Click Beetles in the UK
Click beetles undergo complete metamorphosis, transitioning through egg, larval (wireworm), pupal, and adult stages. Female beetles lay their eggs in the soil, where the larvae hatch and begin feeding on plant roots. The larvae can take anywhere from 1 to 5 years to develop fully, depending on environmental conditions such as soil temperature and moisture levels.
Wireworms cause the most damage in early spring when they are near the soil surface. As temperatures rise, the larvae burrow deeper into the soil to avoid heat and dry conditions. In the autumn, they return closer to the surface to resume feeding as the soil cools. The damage they cause to crops is often noticeable by reduced growth and wilted plants.