The click beetle, a member of the insect family Elateridae, is found across the globe. They are distinguished by their elongated, narrow, streamlined bodies covered by a hard, protective shell. Most species are small, often less than an inch long, and are colored in drab shades of brown, black, or gray. A distinct feature is the shield-like segment behind the head, the pronotum, which has backward-pointing corners. The beetle is primarily known for its unique ability to violently launch itself into the air, accompanied by a sharp, audible sound, which gives it its common name.
The Signature Action: Clicking and Jumping
The click beetle’s namesake action is powered by an internal spring system on its underside, allowing it to jump without using its legs. This specialized mechanism is positioned between the first and second segments of the thorax. It consists of a hard, movable spine, or peg, on the prosternum that fits into a corresponding notch or cavity on the mesosternum.
To prepare for the jump, the beetle bends its body, which loads elastic energy into a specialized section of the exoskeleton. As the beetle holds this bent position, the peg is momentarily latched into the notch, much like a mechanical camera shutter is loaded. When the latch is released, the stored energy is converted into a rapid, explosive unbending motion. This mechanical release creates the loud “click” sound and projects the beetle into the air.
This maneuver is a primary survival strategy when the beetle is flipped onto its back. Since being inverted leaves the insect vulnerable, the sudden jump is a highly effective righting mechanism. The acceleration generated by the system can exceed 300 times the force of Earth’s gravity, launching the beetle several times its own body length. The click also serves a secondary purpose as a defense mechanism, startling potential predators.
Ecological Roles: Diet and Impact
The activities of click beetles are divided between the adult and larval stages, with vastly different ecological and economic impacts. Adult click beetles are generally harmless, playing a neutral or sometimes beneficial role. Many species are nocturnal, feeding on plant-based resources like nectar, pollen, and plant juices. Some adults consume small insects, but they do not typically damage agricultural crops.
The larval form, known as the wireworm, is the stage responsible for most economic concern. Wireworms are generalist feeders, and many species act as beneficial decomposers by consuming decaying wood and other organic matter in the soil. Other wireworm species are predators, hunting and feeding on the larvae of other insects. These functions help enrich soil and naturally regulate pest populations.
However, certain wireworm species are significant agricultural pests due to their diet of living plant tissue. These hard-bodied, cylindrical larvae tunnel through the soil and target seeds, seedlings, roots, and tubers of various crops. They are particularly attracted to the carbon dioxide released by germinating seeds, causing damage to staple crops such as corn, potatoes, carrots, and wheat. This root-feeding behavior can lead to stunted growth, wilting, or the outright death of young plants.
Life Stage Activities: From Wireworm to Adult
Click beetles undergo complete metamorphosis, progressing through four distinct stages: egg, larva, pupa, and adult. The adult female lays eggs in the soil, often near plants or rotting wood, ensuring the emerging larvae have an immediate food source. Once hatched, the insect enters the wireworm stage, which is the longest and most impactful phase of its life cycle.
This larval period typically lasts two to six years, though some species may persist for up to 11 years. Wireworms are subterranean, spending their entire larval life tunneling and moving vertically through the soil profile in response to moisture and temperature changes. This prolonged existence below ground is why their feeding habits can cause cumulative damage to successive crops in a single field.
When fully grown, the larva constructs a chamber in the soil and pupates. This resting stage lasts for a few weeks in the summer or fall. The adult beetle emerges from the pupal case, sometimes remaining in the soil over winter before digging its way to the surface the following spring. The adult stage is comparatively short, lasting only a few weeks to months, and is primarily dedicated to mating, egg-laying, and completing the cycle.