Chiggers

Chiggers are the immature stage of certain mites that live in overgrown brushy or grassy areas, especially where small rodents are abundant. People pick up chiggers while in shady, humid areas near stream banks, under or around trees, or in berry thickets. Chiggers are more active in early summer but can persist much later.

Once on board, chiggers attach and feed where the skin is thin, tender, or wrinkled, or where clothing is tight. Their digestive enzymes liquefy skin cells causing small red welts and intense itching that begins a few hours after chiggers have fed. Chiggers do not burrow into the skin or feed on blood. If undisturbed, these mites may remain attached and feed for 3 or 4 days.

Personal Protection

  • Avoid walking through unmowed fields, brush, and other overgrown areas. Instead, walk in the center of mowed trails to avoid brushing up against vegetation where chiggers congregate.
  • When hiking or camping in potentially chigger-infested areas, wear long pants that are tucked into boots or socks and long sleeve shirts. Clothing made of tightly woven fabrics will tend to keep chiggers from reaching the skin as easily.
  • Apply an insect or tick repellent. Products containing diethyl toluamide (DEET) or permethrin (clothing treatment only) are most effective. Be sure to read and follow container directions for use when applying.
  • Showering or bathing immediately after coming indoors effectively removes chiggers that have not yet attached. If that is not possible, thoroughly and briskly rubbing your skin with a dry towel may remove many chiggers before they are able to attach and feed.

Reducing Discomfort from Bites

  • Apply over the counter anti-itch medication (hydrocortisone, Calamine lotion, etc.)
  • Physicians may recommend oral Benadryl or a prescription strength steroid cream

Controlling Chiggers Outdoors

Reducing Site Suitability

While most common in wild overgrowth, chiggers may become established in yards, parks, camps, picnic sites, and recreation areas. Effective vegetation management can make these locations less suitable for chiggers and may greatly reduce infestations. Pruning trees and bushes and close mowing allows more sunlight into an area and lowers humidity. Removal of scrub brush piles and accumulated debris reduces protection for small mammals and other animals that are important hosts for chiggers. These environmental modifications produce conditions that are less suitable for chiggers and can provide a more long-term solution.

Insecticides

Insecticide sprays may temporarily reduce chigger activity but these alone are not a solution. Sprays are most effective when directed into “hot spots” where chiggers and their animal hosts are known to be abundant. Pay particular attention to borders and fences between wooded or brush areas and the lawn, around ornamental plantings, beside foot paths, and the dog house.

Products containing bifenthrin (Ortho Home Defense MAX), carbaryl (Sevin), cyhalothrin (Spectracide Bug Stop Indoor + Outdoor Insecticide), and permethrin (various brands) can be effective. A single application during late-April or May is often all that is required, although in severe infestations, treatment may need to be repeated. Apply according to label instructions and do not spray flowering plants. Thoroughly wet the ground and vegetation up to a height of about 3 feet. Keep people and pets off treated areas until the vegetation is completely dry.

 

By Lee Townsend and Mike Potter, Extension Entomologists

 

Posted in Human Pests