Bites
Chigger larvae do not burrow into the skin, nor suck blood. They pierce the skin and inject into the host a salivary secretion containing powerful, digestive enzymes that break down skin cells that are ingested (tissues become liquefied and sucked up). Also, this digestive fluid causes surrounding tissues to harden, forming a straw-like feeding tube of hardened flesh (stylostome) from which further, partially-digested skin cells may be sucked out. After a larva is fully fed in four days, it drops from the host, leaving a red welt with a white, hard central area on the skin that itches severely and may later develop into dermatitis. Any welts, swelling, itching, or fever will usually develop three to six hours after exposure and may continue a week or longer. If nothing is done to relieve itching, symptoms may continue a week or more. Scratching a bite may break the skin, resulting in secondary infections. However, chiggers are not known to transmit any disease in this country.
Control Measures
Skin Care
After returning from a chigger-infested area, launder the field clothes in soapy, hot water (125°F.) for about half an hour. Infested clothes should not be worn again until they are properly laundered and/or exposed to hot sunshine. Unlaundered clothes or those laundered in cool water will contain the biting chiggers to again reinfest your skin. As soon as possible, take a good hot bath or shower and soap repeatedly. The chiggers may be dislodged, but you will still have the stylostomes, causing the severe itch. Scratching deep to remove stylostomes can cause secondary infections. For temporary relief of itching, apply ointments of benzocaine, hydrocortisone, calamine lotion, New Skin, After Bite, or others recommended by your pharmacist or medical doctor. Some use Vaseline, cold cream, baby oil, or fingernail polish. (The sooner the treatment, the better the results.)
Prevention
Mowing of briars, weeds, and thick vegetation and close clipping of lawns, to eliminate shade and moisture, will reduce chigger populations, and permit sunlight and air to circulate freely. Chigger larvae can penetrate many types of clothing, but high boots and trousers of tightly woven fabric tucked into stockings or boots help deter them.
Before going into an area where chiggers may be present, protect yourself by using a repellent such as deet (Off MGK, Muskol, Detamide, Metadelphene, Repel, Diethy-toluamide) or permethrin available at many drugstores or hardware stores. Deet-based repellents are effective for only a few hours, whereas permethrin-based repellents are for use only on clothing and effective for several days. Apply the repellent to both the skin and clothing, especially on hands, arms, or legs, if uncovered, and to clothing openings at cuffs, neck, waistband, and upper edges of socks. Follow label directions since repellents may damage plastics, nail polish, and painted or varnished surfaces. Do not use indiscriminately as severe human allergies can develop. Keep moving since the worst chigger infestations occur when sitting or laying down in a sunny spot at midday with temperatures above 60°F. If possible, stick to roads and trails.
Insecticides
Treating known chigger trouble spots is quicker and less expensive than treating an entire area. Place six-inch squares of black cardboard on edge in the grass and observe for a few minutes. Any small, yellowish or pinkish chiggers present will climb rapidly to the top of the square and congregate there. Make tests in 10 to 12 different spots such as grass, dead leaves, briars, weeds, etc. Unless the entire area is infested, treat only the spots where control is desired such as grass around picnic tables, lawn chairs, or recreational equipment. Chiggers tend to concentrate in "mite islands" while nearby spots are free of them. They become rather inactive at temperatures below 60°F.
Outdoor sprays of chlorpyrifos (Dursban), carbaryl (Sevin) or diazinon will give control. Only the licensed pest control operator or applicator can use certain formulations of propoxur (Baygon), cyfluthrin (Tempo), or fluvalinate (Marvik, Yardex). Treat the grass, shrubs, and trees in lawns, parks, campgrounds and golf courses, if needed, keeping humans and pets off treated areas until dry. Retreatment may be needed after two to three weeks in heavy chigger infestations. Before using any pesticide, always read the label and follow directions and safety precautions.
Do not wear dog or cat flea collars on your ankles or cattle ear tags on your shoes to ward off chiggers. It is very dangerous resulting in chemical skin burns and toxic effect to the wearers.
2006-07-07 04:39:32
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answer #7
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answered by JOHN B 3
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