In honor of the Master Gardner advanced training class on entomology that started this month, I resolved to write about "bugs." The question of which bug was settled when I found a bark scorpion last week.

A search for "scorpions" on the World Wide Web yielded several sites with information about these creatures, but the bonanza was at a site authored by Dr. Scott A. Stockwell at the Walter Reed Biosystematics Unit in Washington, D. C. called "Scorpion du Jour." http://www.wrbu.org/scorpions/sc_du_jour/scorpion_du_jour.html Here are some of the highlights of the information on bark scorpions found there:

* The scientific name of the bark scorpion is Centruroides exilicauda (formerly Centruroides sculpturatus). The generic name Centruroides is from the Greek words centr-, meaning "pointed," and ur, meatung "tail." The specific name exilicauda is from the Latin words meaning "slender" (exili- ) and "tail" (cauda).

* Centruroides exilicauda is found in southeastern California, Arizona, Nevada, southern Utah, and southwestern New Mexico in the United States as well as the Baja Peninsula and western Sonora. It is most commonly found under rocks, logs, the bark of trees, and other surface objects. Unfortunately bark scorpions are also one of the few varieties that commonly invade homes.

* All scorpions are venomous, but the venom is seldom lethal to humans, although scorpion stings, like bee stings, can induce an allergic reaction in some people. Dr. Stockwell provides statistics from the Arizona Poison and Drug Information Center (APDIC) that show out of 438 reported stings by bark scorpions, none were fatal. APDIC recommends cleaning the site with soap and water, applying cool compresses, elevating of the affected limb to approximately heart level, and taking an analgesic as needed for minor discomfort. Just to be on the safe side, they also recommend you give them a call at 1-800-362-0101 if you are stung.

* Dr. Stockwell recommends that the key to keeping scorpions out is sealing the house. You must remove all debris (wood piles, rock piles, brick piles, etc.) and eliminate all landscaping which, of course, is realistically impossible. No baits have been developed, and parasites and predators of the scorpion are just as obnoxious as the scorpions themselves. There are no specific pesticides recommended for scorpions, but pesticides that kill cockroaches and other scorpion delicacies will help to control their numbers.