Chigger Mites

Facts, Identification & Control

Scientific name

Trombicula spp.

Appearance

What Do They Look Like?

  • Size: Chigger mite adults are larger than the nymphs and larvae, being about 1 mm (@ 1/25th inch long). Chigger larvae are very small, about 0.15 to 0.25 mm long.
  • Color: Nymphs are reddish orange while adults are bright red.
  • Legs: Larvae have six legs while nymphs and adults both have eight.

How Did I Get Chigger Mites?

Chigger mites have fairly simple needs when it comes to their habitat. They require moisture, shade, a source of food and little else. Chigger mites attach to people, pets, and other hosts as they pass through the following areas:

  • Overgrown lawns
  • Woods
  • Flowerbeds and gardens

How Serious Are Chigger Mites?

In comparison to other parasites, chigger mites are a low-level concern unless you are a hiker or are outdoors for other activities such as hunting and camping. These pests only target and feed on humans during their larval stage. Chiggers do not remain attached to their host for more than a few days, do not spread diseases, do not infest homes, and do not burrow or bite to consume a blood meal as do ticks and mosquitoes.

When chigger mites latch onto the skin, it results in an intense rash, which if scratched excessively, can result in infection. Larval mites cause these rashes when injecting a skin cell destroying substance that causes irritation, rash, and intense itching. Itching caused by chigger bites does not occur until about three or more hours after the bite.

Signs of Infestation

The symptoms that occur from the feeding activity of chigger mite larvae are generally the most obvious sign of an infestation. In addition, the appearance of nymphs and adults in or on the soil and vegetation also can signal the presence of chigger mites. However, chigger mites are so small that actually seeing any stage of this mite is difficult.

Often, a person with chigger mites will have a lot of them on their body at one time. The most common bodily locations are around the tops of socks and shoes, waistline, the groin area, armpits, and most any bodily part where clothing fits snugly against the skin.

How Do I Get Rid of Chigger Mites?

What You Can Do
When venturing into the woods or other areas where chiggers are located, wear clothing treated with permethrin clothing repellent. Also consider applying insect repellent to parts of your body where chigger larvae may infest.

What Orkin Does
Chigger management is generally a task best suited for your pest management professional (PMP) since it is so difficult to determine the source of the problem. Your PMP will be familiar with techniques that work to inspect for and locate chigger mites. They will target the areas where chiggers are abundant rather than using chemical products throughout the entire property. Also, their knowledge about chigger habitat and habitat modification will be valuable to reduce the places where chiggers can successfully live and develop.


Behavior, Diet & Habitat

There are many species of chiggers located within the U.S., but the most common species encountered by people are trombicula alfreddugesi and trombicula splendens.

Life Cycle
Chigger mites develop by going through 4 distinct life stages – eggs, larvae, nymphs, and adults. The life cycle begins when the female adult lays eggs in or on the soil. After the eggs hatch, larvae crawl upon the soil surface and low growing vegetation where they wait until they find a suitable host to attach to and begin to feed. The larval stage is the only parasitic stage of the mite’s life cycle.

Depending upon the temperature and other environmental factors, chigger mites complete one life cycle in about 2 – 3 months. In favorable climates, they may complete 3 generations per year.

What Do They Eat?
Preferred hosts of the larvae are people, snakes, birds, and many species of small mammals. Chigger mite larvae penetrate the host’s skin and inject a secretion that breaks down and digests the skin cell. The larvae then suck up the digested liquid. The host’s skin becomes hard and a tube forms in which the chigger’s mouthparts remain until feeding stops or the chigger is dislodged. Generally, they feed several days (if not dislodged), drop to the ground, and develop into mite nymphs.

Nymphs and adults do not infest the same hosts as larvae. Instead, they feed on the eggs and young of insects and other small arthropods in and on the soil surface.

Geographic Range
Trombicula alfreddugesi and splendens are common in the southeastern and Midwestern states, plus some areas in the Great Lakes and the Mississippi River valley regions. However, even in areas of preferred habitat, chigger populations may be sparse in one area and very heavily concentrated in a nearby area.

Where Do They Live?
Preferred chigger mite habitat are areas of thick, scrub-type vegetation, grassy areas where the soil is undisturbed and they can “latch” onto hosts that may be passing by. Generally, these pests are found in rural, less disturbed areas, but can persist for several years in their habitat associated with new housing subdivisions.

Reproduction

Adult males move around their preferred habitat and deposit very tiny capsules of sperm known as spermatophores that the females will find and insert into a structure on their body known as the genital pore. About two weeks after fertilization of the eggs, females drop fertilized eggs onto the soil surface.

Chiggers on Pets

For cats, chiggers may be found on the inside of the animal’s ears. The reaction of dogs and cats to chiggers range from scratching at the site of infestation to the animal being unaware of the chigger’s presence. People do not get chiggers from contact their pets. Rather, chiggers on both pets and people almost always mean that both were outside in areas where chiggers were numerous.