Garden Mastery Tips
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November/December 2007 |
Beneficial Beetles
Beetles, of the Order Coleoptera, make up the most species of insects, and in fact are the largest group of animals, on earth. There are about 350,000 species, with nearly 30,000 in the United States alone.
Because Beetles are such a large, diverse group, some species eat nearly every kind of food. They feed on all parts of living and dead land plants. They can be found in virtually all habitats, including aquatic, though none occupy deep sea or the polar regions.
Gardeners encounter many types of beetles – the good, the bad, and the ugly. Many are famous, such as the scarab beetle, considered sacred by the ancient Egyptians. Others are infamous, such as the boll weevil, which has cost cotton producers billions of dollars since it first entered the United States.
All beetles are characterized by a pair of hardened forewings. Known as elytra, they form a protective casing for the membranous hind wings and usually meet in a straight line along the back of the abdomen. Most beetles have well developed chewing mouthparts. Beetles exploit almost every ecological niche and exhibit a tremendous range in size.
There are several which we will discuss that are considered beneficial to gardeners:
Ground Beetle – These beetles are usually shiny, and come in various colors, though black is common. Adult ground beetles range from 1/8 to one inch long. They feed on many soil-inhabiting pests such as root maggots and cutworms. Snails and slugs are eaten by some types.
Rove Beetle – These beetles are narrow and elongated, and may resemble a tiny scorpion when the tip of the abdomen in held up in the air. They are fast moving and measure 1/10 to one inch long. Some species of rove beetle prey upon aphids, mites, slugs, snails, fly-eggs and maggots. They also eat and help to break down organic matter.
Soldier Beetle – The adult soldier beetle is about ½ inch in length, with a narrow, black abdomen and bright red head or thorax. The larvae is various shades of orange with black markings. Soldier beetles prey on aphids, caterpillars, grasshopper eggs, and other garden insects.
Lady Beetle – Also known as the ladybug, these beetles come in many different colors, plain or spotted. The larvae are very valuable, and are soft-bodied and alligator-shaped with black and orange markings. An in-depth discussion of this beneficial insect may be found in the May 2006, article on this web site, “The Beneficial Ladybug.”
References
Sunset Western Garden Problem Solver, by the Editors of Sunset Books and Sunset Magazine, Sunset Books, Inc. Menlo Park, CA 1998.
"Beetles" http://www.si.edu/Encyclopedia_SI/nmnh/buginfo/beetle.htm, retrieved 9/4/2007.
"Beetle", http://en.wikipedia.org/wiki/Beetle retrieved 9/2/2007.