Eyed Click Beetle – Alaus oculatus

Eyed Click Beetle – Alaus oculatus
Family Elateridae – Click Beetles
Live adult beetles photographed at Vero Beach, Florida, USA.    Beetles Index

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The eyed click beetle is found in the southern U.S. as far west as Texas. At up to 2 inches long, it is one of the largest known "click" beetles in the family Elateridae. The huge false eyespots make it readily identifiable; it is thought these startle predators into thinking they are confronting an animal much larger than it really is. The true eyes are located behind the base of the saw-toothed antennae. Most click beetles are considerably smaller and not as conspicuously marked.

All click beetles have a defense mechanism responsible for their common name; when disturbed, the beetle launches itself high into the air with an audible click. This feat of strength is accomplished through the use of a stiff chitinous spine on the underside of the prosternum that fits into a groove on the mesosternum; the beetle build pressure against the spine which is suddenly released causing the two segments to spring violently apart. It is said the beetle is able to transition into winged flight during these excursions.

Click beetles undergo complete metamorphosis: Egg – larvae – pupa – adult. Some species of click beetle have larvae that have a hard shell, commonly called "wireworms." These grubs can be serious agricultural pests, feeding as they do on the roots of plants (corn and other cereal grains are often attacked) during their 1-3 year portion of the life cycle. Wireworm larvae are hard, smooth, slender, wire-like worms varying from 2 to 1 inches in length when mature. They are a yellowish-white to a coppery color with three pairs of small, thin legs behind the head. The last body segment is forked or notched.

Wireworms usually take three to four years to develop from the egg to an adult beetle. Most of this time is spent as a larva. Generations overlap, so larvae of all ages may be in the soil at the same time. Wireworm larvae and adults overwinter at least 9 to 24 inches deep in the soil. When soil temperatures reach 50 to 55 degrees Fahrenheit during the spring, larvae and adults move nearer the soil surface. Adult females emerge from the soil, attract males to mate, then burrow back into the soil to lay eggs. Females can re-emerge and move to other sites where they burrow in and lay more eggs. This behavior results in spotty infestations throughout a field. Some wireworms prefer loose, light and well drained soils; others prefer low spots in fields where higher moisture and heavier clay soils are present.

Larvae move up and down in the soil profile in response to temperature and moisture. After soil temperatures warm to 50 F, larvae feed within 6 inches of the soil surface. When soil temperatures become too hot (>80 F) or dry, larvae will move deeper into the soil to seek more favorable conditions. Wireworms inflict most of their damage in the early spring when they are near the soil surface. During the summer months the larvae move deeper into the soil. Later as soils cool, larvae may resume feeding nearer the surface, but the amount of injury varies with the crop.

Wireworms pupate and the adult stage is spent within cells in the soil during the summer or fall of their final year. The adults remain in the soil until the following spring.

Wireworm infestations are more likely to develop where grasses, including grain crops, are growing. Crops susceptible to injury include small grains, corn, potatoes, sugar beets and vegetables. Legumes are less likely to be injured. Wireworms damage crops by feeding on the germinating seed or the young seedling. Damaged plants soon wilt and die, resulting in thin stands. In a heavy infestation bare spots may appear in the field and reseeding is necessary. [1]

1. Philip Glogoza, North Dakota State University Wireworm Management for North Dakota Field Crops with permission
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Order Coleoptera: Beetles are the dominant form of life on earth: one of every five living species is a beetle. Coleoptera is the largest order in the animal kingdom, containing a third of all insect species. There are about 400,000 known species worldwide, ~30,000 of which live in North America.  Beetles live in nearly every habitat, and for every kind of food, there's probably a beetle species that eats it.
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