Chiggers bring itch to summer activities

Adult chigger (left) and chigger larva. The tiny larva (0.25 mm) is the chigger&rsquo;s only biting life stage. The adult is a predator on other soil-dwelling arthropods. Adult chigger (left) and chigger larva. The tiny larva (0.25 mm) is the chigger’s only biting life stage. The adult is a predator on other soil-dwelling arthropods. Summertime usually means picnics, fun in the sun and good times. Summer can also mean time when small mites called chiggers can become active.

Chiggers can turn a normal outing into a nightmare if they end up crawling on you and causing the small, red itchy welts you might see after being outdoors.

Texas AgriLife Extension Program Specialist-IPM Kim Schofield said that chiggers develop through four life stages — egg, larva, nymph and adult. The larval stage is the one that usually can feed on humans. The six-legged larvae first hatch from eggs and then climb up onto vegetation to have better access so they can crawl onto a passing host. Only the larval stage feeds on humans and animals.

She said that chigger larvae prefer to bite people in places where clothing fits tightly over the skin such as around the waistline, under socks, or where the skin is thin or creased such as around the ankles or the back of knees. The larvae insert their mouthparts into a skin pore or hair follicle, and then inject a digestive fluid to dissolve skin cells. This results in itchy, reddish welts on the skin.

After feeding, the larvae then drop off of the host to molt into eight-legged nymphs which then molt into adults. Chigger nymphs and adults feed on small insects and insect eggs found in the soil. Under favorable conditions, most chiggers complete their development from egg to adult in 40 to 70 days.

To prevent chigger bites, Schofield suggests avoiding sitting on the ground when camping, picnicking or working outdoors. Tightly-woven socks, long pants, long sleeved shirts and high shoes can be worn to eliminate any possibility of entry to the skin. Also tuck pant legs inside boots and button cuffs and collars as tightly as possible to prevent chiggers from climbing inside your clothes.

Apply repellents such as DEET can be applied to both the skin and clothing or permethrin to clothing only. Powdered sulfur is another repellent that can be dusted around the opening of your pants, socks, and boots or rubbed on skin such as over legs, arms and waist.

If ex posed to chiggers or chigger bites, Schofield suggests washing clothes in hot, soapy water to kill chigger larvae. Also, take a hot bath or shower and soap repeatedly; creams or ointments containing hydrocortisone or calamine lotion can be applied to temporarily relieve the itching caused by chigger feeding.

Chiggers can sometimes becomeaprobleminhome lawns. Keeping grass cut short and vegetation well-trimmed can raise soil temperatures and lower humidity enough to make lawns less hospitable to chiggers.

Occassionally, chemical control may be needed. Insecticide sprays may provide some temporary reduction of chiggers and can be effective when applied in areas where chiggers and their animal hosts are living and/or traveling. Insecticides containing carbaryl, permethrin, cyfluthrin are some suggestions for control, she said.

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2011-07-14 digital edition


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