With more than 300,000 species described, there are more species of beetles than any other kind of animal. Like all insects, beetles have three body parts - head, thorax and abdomen - and six legs attached to the segments of the thorax. Most adult beetles have 2 pairs of wings. The front pair, called the elytra (singular elytron), are hardened and can be quite colorful. The membranous back pair fold up and are protected under the elytra. In most species, the elytra also protect the entire top of the abdomen. Beetles belong to the insect order Coleoptera, a word derived from the Greek, koleos, meaning a sheath, and pteron, meaning a wing. Elytra is derived from another Greek word for sheath. The presence of elytra is characteristic of beetles.

In order to fly, beetles elevate the elytra freeing the membranous wings to do the work. In the larger beetles, like the Green Fruit Beetle whose adults fly between late July and late September, the elytra are not lifted very high. In some smaller beetles, like the ladybird beetles (often called ladybugs), the elytra are lifted high enough that, from the side, the insects look like small sailboats with balloon sails. This characteristic appearance can be used to distinguish small flying beetles from other small airborne creatures. Beetles whose elytra have been removed cannot fly. Some species, such as the Armored Stink Beetle (one of the large black beetles that adopts a threat position in which it appears about to stand on its head), cannot fly because the elytra are fused together and the second set of wings do not develop.

Most beetles have chewing mouth parts both as juveniles and as adults. Many are important predators. The Convergent Ladybird Beetle, one of the commonest ladybird beetles around the Center, feeds on aphids throughout its life. (In the winter time, these beetles congregate in large number in the mountains. In spring the clusters break up, and on warm days flying beetles fill the air.) Their common name is derived from the two short whitish-colored dashed lines on the black, first segment of the thorax rather than their winter behavior. Along the shoreline, adult and juvenile tiger beetles prey on small creatures. As adults, many species visit flowers, usually those with exposed pollen, but are not usually efficient pollinators because their bodies are relatively smooth. These species, such as the Green Fruit Beetle, eat the pollen and sometimes other parts of the flower heads as well. Wood-eating beetles, such as the bark beetles found in Torrey Pines State Park, have had a major impact on drought-stressed trees. Beetles, like the dung and grain beetles, recycle animal and plant material.

Beetles are important contributors to our environment. Watch for them around the Center.

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Ron Lyons (volunteer 1990-1999)
Chula Vista Nature Center, 1000 Gunpowder Point Drive, Chula Vista, CA 91910-1201