In the 1930's a South American freighter docked in Mobile, Alabama with more than cargo on board. Somewhere in the ship, probably in the ballast, a queen and her court waited to disembark into a new land. The red imported fire ant arrived by sea, escaped, and now occupies more than 300 million acres of land in the gulf coast states and as far north as North Carolina, Tennessee, Arkansas, and Oklahoma. This pernicious insect also infests portions of New Mexico and California. Local infestations have been found in Virginia and Maryland but it is still not clear how long these colonies can persist in northern climes. Four years ago I discovered a colony in a landscape bed outside of a bank in Columbia, MD. Another colony was found on the University of Maryland Campus two summers ago. This summer my friends at the Maryland Department of Agriculture have seen a spate of infestations in landscapes and restaurants where fire ants have traveled with landscape plants and tropical potted plants from the quarantine zone in the South. Antz schmantz? What's the big deal with ants?
The fire ant anchors itself with its jaws then curls its abdomen beneath to inject its venom into the skin.
My first serious encounter with fire ants happened on a bug-collecting trip in Florida. I was squirming through vegetation and stopped to photograph a dragonfly. I knelt in a fire ant nest and within seconds my right leg was covered with dozens of stinging, biting ants. The sting of a fire ant is unique, something less than the bite of a Doberman but more than that of a mosquito. The defending ant grasps the skin with powerful jaws. She curls her abdomen beneath and stabs the flesh of the adversary with a stinger injecting potent venom that burns like fire for several minutes. She can administer several stings until forcibly removed or crushed.
Three days after a fire ant attack my leg was red and itchy.
The normal reaction to one or a few bites will be several minutes of memorable pain followed by a small raised pustule. This blister may turn whitish or red. Beginning the day after the attack, my welts itched periodically for several days. As long as the welts do not become infected, which usually occurs by scratching, the pustules and associated redness disappear in less than a week. However, for a small fraction of people, one to five percent, a fire ant sting can be more dangerous. Two weeks ago an elderly women in South Carolina died after being stung by fire ants while gardening. Following a sting people allergic to fire ants may have symptoms including itching and hives over much of the body, upset stomach and cramps, swelling of the tongue and throat, headache, tightness in the chest, difficulty breathing, disorientation, and loss of consciousness. Anyone experiencing these symptoms following the sting of a fire ant or any stinging insect such as a bee or wasp should seek medical attention immediately. People with known allergies to insect stings should be especially careful when visiting locations infested with fire ants because there may be cross sensitivity to fire ant allergens and those of other stinging insects.
Even small fire ant mounds like this one contain thousands of workers ready to defend the colony to death.
While it might be difficult to distinguish a fire ant from other less noxious ants crawling side by side on the pavement, their behavior and nests are dead giveaways. Fire ants build colonies in the ground that may be several feet in diameter and more than two feet in height. A single large fire ant mound will contain dozens of queens each capable of laying more than 1,000 eggs per day. Colonies may contain more than a quarter of a million ants. These are ants with an attitude. Workers are highly aggressive when a predator or an entomologist?s knee threatens the colony and will swarm onto the intruder in seconds and begin a mass attack. To avoid fire ant stings avoid the ants. Learn what mounds look like and stay clear of them. Teach children to recognize and avoid them. Inspect picnic areas including tables and benches as well as lawn areas before using them. If you live in an infested area, wear closed shoes rather than sandals while gardening. Tuck your pant legs into your socks to prevent ants from moving beneath clothing and up your legs to sting. Treating them with very hot water or potent insecticides applied as granules or drenches may eliminate individual mounds. Professional pest control operators have the skill and tools to eliminate infestations. Recently, a remarkable fly has been imported and released in the South as a biological control agent for fire ants. The female fly pierces the body of the ant and deposits an egg inside. The egg hatches into a maggot that eats the entrails of the fire ant and works its way to the victim?s head. The maggot consumes the tissue connecting the ant?s head to its thorax decapitating the ant in the process. Sweet! If you live in areas outside of the zone of known infestations, and you believe that you have found a fire ant colony, please contact the officials at your state Department of Agriculture. A map of the generally infested zone can be seen at the following web site: http://pubs.caes.uga.edu/caespubs/pubcd/B1191.htm#Fig1
References
Special thanks to Desiree Adib and Allison Girvin from Good Morning America for providing the inspiration of this week?s Bug of the Week. To learn more about fire ants and their stings, please visit the following web sites.
http://pubs.caes.uga.edu/caespubs/pubcd/B1191.htm#Methods
http://www.ext.vt.edu/pubs/entomology/444-284/444-284.html http://www.emedicine.com/DERM/topic607.htm