CHIGGERS

Chiggers are tiny bright red-colored mites, 1.25 mm long, found in second growth areas, blackberry patches, orchards, woodlands and in pine straw.  They pass through four developmental stages:  egg, larvae, nymph and adult.  Eggs hatch in about a week into the six-legged larvae stage (1/50” long).  This is the parasitic stage.  The larvae crawl on the soil until they find a suitable vertebrate host (small mammals, domestic animals, reptiles, poultry, and birds).  They attach themselves to the host and remain until they are fully engorged with fluids and blood.  After feeding, they drop off the host and molt to the nymph stage and then into an adult.   Nymphs and adults feed on insect eggs and small insects.  The entire life cycle is about 60 days.  Depending upon temperature, moisture and location, there may be as many as five generations.

Humans are accidental hosts.  Chiggers that attach to humans are usually dislodged or die within hours.

Chiggers are very active in looking for a host and may spend a few hours crawling over the skin before beginning to feed.  When its piercing mouthparts are inserted into the skin, a fluid is injected that dissolves the cells upon which it feeds.  The chigger does not burrow under the skin.  They feed by sucking up the liquefied tissues.  The human immune reaction to a bite prevents the chigger from obtaining adequate nourishment; therefore they rarely survive long enough for a complete meal.  On other vertebrates they may draw blood and fluids for several days until they become engorged and drop off. 

The injected fluid causes a reddish welt that may last for two weeks, swelling, and itching three to six hours after exposure.  These bites are annoying.  Scratching can break the skin and invite secondary infection.  A hot soapy bath as soon as they are noticed will kill and remove them.  Chiggers prefer to attach themselves on parts of the body where clothing fits tightly; therefore, examine the waistline, ankles, knees, and armpits.  An antiseptic should be applied to the welts.  Nonprescription medications available from drug stores will give temporary relief from itching.  Studies have shown that meat tenderizer rubbed into the welt will alleviate itching.

If you are going into areas where chiggers exist, apply repellents to skin and/or clothing before entering the areas.  Wear protective clothing, and tightly button or tape sleeves, pant cuffs, and collars.

Chiggers may be found in the home landscape.  Keeping the turf mowed removes their protective cover.  To locate chigger infestations in natural areas place a piece of black cardboard edgewise on the ground.  If chiggers are present, they will climb to the top and congregate there.  They will appear as tiny yellow or pink dots moving across the cardboard.  Wear protective clothing and repellant when conducting a survey.  Clear brush from natural areas.  If necessary, spray with insecticides.

References:  “Chiggers”, P. G. Koehler, Cooperative Extension Service, University of Florida

Truman’s Scientific Guide to Pest Control Operations, Gary W. Bennett, John M. Owens, Robert M. Corrigan, Purdue University