Click Beetles

Introduction

Click beetles (Coleoptera: Elateridae) belong to a large family of beetles with hundreds of species in North America. All adult click beetles have an unusual mechanism that allows them to right themselves when they are flipped on their back. They have a projection or peg on the ventral side of the thorax that projects slightly over a small perpendicular ledge. Click beetles can snap the peg into a groove under the ledge with an audible "click.” This movement causes the head to snap back with such force that the beetle can be propelled into the air as much as several inches. This sudden movement probably startles any predators that might have considered the upside-down beetle to be easy prey.

Description

Adult click beetles are flattened, elongate beetles that generally measure 6.4-19.1 mm (0.25-0.75 inch) long. Most are uniformly brown to black in color (Fig. 1). Some species have contrasting patterns of spots or longitudinal stripes (Fig. 2).

Adult eastern eyed click beetles (Alaus oculatus) are unusually large click beetles found in Virginia. Adults measure about 2.5-5 cm (1-2 inches) long. They have large spots on their thorax that strongly resemble eyes and are thought to be a defense against attack by birds (Fig. 2). Despite some folklore accounts, these eyespots do not glow in the dark. The beetle’s true eyes are located on the head near the antennae.

The larval form of the click beetle is the wireworm, an elongated, cylindrical grub with a hard body and 3 pairs of legs located near the head capsule (Fig. 3). Wireworms are often pale to tan in color with a darker head capsule and tip of the abdomen. Wireworms are found in the soil where they feed on plant seeds, tubers, roots, and underground plant tissues. Some species of click beetles with larger larvae are predaceous on other insects.

Life History

Click beetles have a complete life cycle with egg, larval, pupal, and adult stages. Adult females lay their eggs in the soil. The larvae mature and pupate underground, and the adults dig through the soil to emerge after pupation. Development from the egg to adult stage may take several years for some species. 

Habitat

Click beetles are ubiquitous insects in the landscape. They are found in wooded areas, lawns and fields, gardens, and farmland. 

Damage

Adult click beetles are attracted to bright lights at night. They can be a nuisance around houses and buildings in mid to late summer. Adult click beetles do not bite or sting, but they may try to “click” out of your hand if you pick them up. 

Wireworms can be pests in gardens and turf when they occur in large numbers. Adult click beetles feed on nectar and pollen from flowers and do not cause damage to plants.

Control 

The best way to limit the number of beetles entering houses or buildings is by reducing the outdoor lighting that attracts the adults. Consider leaving outdoor lights off if they are not needed. Lower-intensity lights or motion-activated lights are good choices if outdoor lights cannot be left off. Doors and windows should be in good repair, with tight-fitting seals and screens without holes. Seal cracks, gaps, or holes in foundations and walls to limit the entry of the beetles as well. Individual beetles found indoors can be vacuumed up or controlled with an aerosol insecticide as needed.

Revised 

Theresa A. Dellinger, January 6, 2021.