Released: July 01, 2005

‘05 Weather Creating Paradise for Chiggers

MANHATTAN, Kan. – It’s the heat AND humidity that turn the outdoors into chigger paradise.

Of summertime’s Terrible Three – chiggers, mosquitoes and ticks – chiggers are the only ones that are not bloodsuckers. (They eat the contents of skin cells.) Chiggers don’t transmit diseases – at least in the United States, said Ludek Zurek, medical/veterinary entomologist for Kansas State University Research and Extension.

But, they’re also the most likely to turn memories of the outdoors into sheer misery ... for days.

“Chigger nymphs and adults feed on small insects, other mites and their eggs. Chigger larvae are the only stage that bite people. As soon as they hatch, the larvae start crawling up tall weeds or grass – often in bunches – so they can attach themselves to the first warm-blooded animal that comes along,” Zurek said.

Being prepared for such attacks is humans’ best protection. The entomologist recommends:

* Keep lawns trimmed, so sunlight can reach the ground. Chiggers and ticks do not like direct sunlight and/or low humidity.

* Avoid walking or sitting in tall vegetation or in any grass that isn’t directly exposed to the sun.

* Wear a repellent, carefully following its label directions. Those containing DEET are the best all-round choice. Those with permethrin are only for use on clothing. Traditional sulfur dust remains an effective repellent, but its “rotten egg” smell will repel people, too, once it mixes with sweat.

Chiggers are a mite, not an insect. They’re kin to spiders, scorpions and ticks (arachnids).

Their larvae are small enough they can easily move through the weave of many fabrics. Yet, they can quickly migrate across their host’s skin, looking for the hottest, sweatiest place they can find. They often locate it within minutes.

“That’s one reason their bites so often show up in your armpit, under your waistband and in the groin area – places where they’re also harder to remove,” the entomologist said. “Even so, if you’ve got a row of bites, that means you’ve got a bunch of chiggers attached to you – not just one, moving around.”

Unless washed away in a hot, soapy shower, the larvae may stay attached for several days.

Chiggers start causing problems as soon as they’re in place, however. Typically, larvae have been feeding for three to six hours before their host’s skin starts to itch.

“Because you’ll know where they are when you start itching, you may be able to see them if you look closely and have good eyesight,” Zurek said.

At best, each will appear to be a tiny dark spot, he added. The average chigger larva is 10 times smaller than one-fourteenth of an inch long. About 1,000 could line up down the length of a dollar bill.

What’s called a chigger bite is actually a reaction in the skin around the bite site, Zurek said. Chiggers often get a head start for their tiny mouthparts by working in or near a pore or hair follicle or in a wrinkle or skin fold where skin is thinner. There, they inject powerful saliva, which digests/dissolves skin cells. This saliva, in turn, triggers the skin to produce histamines – to develop an allergic reaction.

Other than time, few things can help ease this allergic reaction, even after the chiggers are gone and the saliva injections have stopped.

“So far, applying the combination of a sealant and an antihistamine is the best approach. For example, I use Caladryl because it contains both calamine lotion and the antihistamine benadryl,” Zurek said. “For first aid outdoors, sunscreens with benzocaine can be helpful. Even Vaseline or baby oil can act as sealants to help control itching.”

Folklore has long held that chiggers burrow under the skin and that bite victims need to suffocate the tiny mites to stop the itching. One popular “cure” is to paint the bites with nail polish. More dangerous home remedies include bathing with bleach, alcohol or turpentine.

“I doubt the nail polish would hurt much, and it might serve as sort of a sealant,” the entomologist said. “But the other ideas are simply wrong.”

Zurek does not recommend spraying lawns to kill chiggers. The effective sprays also kill hosts of beneficial insects and are, at best, an imperfect and short-term solution. Spraying can at least the reduce numbers, however, in a small, deeply shaded and heavily infested area. County and district K-State Research and Extension offices can provide direction on the best sprays to use.

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K-State Research and Extension is a short name for the Kansas State University Agricultural Experiment Station and Cooperative Extension Service, a program designed to generate and distribute useful knowledge for the well-being of Kansans. Supported by county, state, federal and private funds, the program has county Extension offices, experiment fields, area Extension offices and regional research centers statewide. Its headquarters is on the K-State campus, Manhattan.

Story by:
Kathleen Ward
kward@oznet.ksu.edu
K-State Research& Extension News