The Indian Trail Master Naturalists took a nature hike last week and I was prepared to meet the enemy. Long pants, sox and rubber bands around my pant legs would surely keep the chiggers at bay. A healthy spray of insect repellant containing DEET (N,N-diethyl-meta-toluamide) was my other line of defense. But, somehow, over 50 of these critters came home with me.
Chiggers are more closely related to spiders than insects; they belong to the class Arachinida, along with scorpions and ticks. It is the larva, the immature stage of a mite, that causes the irritating bite.
Several species of chiggers reside in Texas; but, only two are annoying. One, Eutrombicula alfreddugesi, inhabits grassy and weedy areas, overgrown berry patches and edges of woods. The other, Eutrombicula splendens, prefers moist habitats like swamps, bogs and rotten logs. Even in these favorable habitats, their distribution varies. They may be heavily concentrated in one spot and virtually absent in another.
Chiggers actually prefer birds, reptiles, rodents and other small mammals as hosts. We are less ideal because of our adverse skin reactions and scratching. They grab onto shoes or clothing and explore for several hours before selecting a place to feed. They favor areas where the clothing is tight and skin is thinnest. Areas along the waist, groin and behind the knee are prime targets.
Contrary to common belief, chiggers do not burrow into our skin or suck blood. They pierce the skin with their sharp mouthparts and inject a digestive enzyme, disintegrating skin cells for food. Itching typically begins within 3 to 6 hours after an initial bite, followed by development of reddish areas and sometimes clear pustules or bumps. As the skin becomes red and swollen, it may completely envelop the feeding chigger, making it appear that the chigger has burrowed into the skin. Itching typically peaks at 24 to 48 hours after chigger bites occur, but redness and itching may persist for a week or more.
Chiggers pass through four life stages: egg, larva, nymph and adult. During the early, warm days of spring, females deposit their eggs in leaf litter and damp soil. The larvae that hatch have yellowish to light-red hairy bodies, six legs and measure less than 1/150 inch long. Only the larvae or “chigger” stage is parasitic. Once it finds a host, it usually feeds only three days before dislodging itself, dropping off to digest its meal and molting into its nymph stage.
Nymphs and adults have eight legs and are predators, feeding on small insects and insect eggs found in the soil. Adult Eutrombicula mites are about .0394 inch long, with a velvety texture and brilliant red coloring. They sometimes are seen walking in leaf litter or along the edges of stones or concrete and often are referred to as “red bugs.”
For optimal defense against chiggers, apply products containing permethrin (such as Permanone® Tick Repellent) to your clothing. The treatment is long-lasting and will be effective through several washings. Combine permethrin-treated clothing and DEET applied to the skin if you will be in areas heavily infested with chiggers. When returning home, promptly take a warm bath and scrub off any mites before they take hold. Wash your clothes before wearing them again.
Antihistamines such as oral Benadryl®, anti-itch creams (camphor and menthol, calamine or pramoxine), or hydrocortisone ointments give the best relief from the intense itching. It’s also wise to apply antiseptic ointment to prevent infection on bites that have been abraded by clothing or scratching.
Now, did the chiggers dampen the fun I had on the nature walk? Scratch that thought! I added three plants to the list of wildflowers I can now identify: meadow pink (Sabatia campestris), Illinois bundleflower (Desmanthus illinoensis) and blue sage (Salvia azurea). Moreover, the experience motivated me to learn about these dreaded hitchhikers!
Submitted by Mox Moxley, Master Naturalist