Chiggers are often misunderstood pests, frequently confused with insects like fleas regarding how they move. Chiggers do not jump like fleas. They are tiny larvae that rely on crawling and passive transfer to find a host. Fleas possess specialized leg structures allowing them to launch themselves vertically, a ballistic form of travel chiggers are physically incapable of performing. This distinction in movement results from their different biological classifications and feeding strategies.
Identifying the Chigger
Chiggers are not insects but mites, belonging to the class Arachnida along with spiders and ticks. The chigger that affects humans is the larval stage, which is the only parasitic phase of its life cycle. These larvae are nearly microscopic, measuring only about 0.15 to 0.3 millimeters in length.
In this parasitic stage, the larva possesses six legs and appears yellow, orange, or bright red. Once they mature, they develop into nymphs and eventually adults with eight legs, but these later stages are harmless to humans. Adult mites feed on small arthropods and plant material, spending their lives in the soil and leaf litter.
How Chiggers Find and Attach to a Host
The chigger larva’s strategy for locating a host depends on slow movement and environmental detection. They are found in moist, shaded areas with dense vegetation, such as tall grass, weeds, and wooded edges. Once hatched, the larvae climb to the tip of a blade of grass or a leaf, a behavior known as “questing.”
During questing, the chigger extends its front legs, sensitive to cues like shadows, vibrations, and carbon dioxide, which signal a host’s presence. Transfer is entirely passive; they must physically grab onto clothing or skin as the host contacts the vegetation.
After hitching a ride, the chigger crawls along the host’s body, often for several hours, seeking a suitable feeding site. They prefer areas where clothing fits tightly, such as waistbands, sock lines, and the backs of knees, because these spots impede migration and offer thinner skin. This crawling process explains why bites often appear in clusters around constricted areas.
The Chigger Bite and Symptoms
Contrary to misconception, the chigger does not burrow into the skin to feed. Instead, the larva uses its mouthparts to pierce the skin and inject a salivary secretion containing digestive enzymes. These enzymes break down the surrounding skin cells, liquefying the tissue.
The host’s immune system reacts to this injection by hardening the tissue around the feeding site, forming a rigid, straw-like structure called a stylostome. The chigger then feeds on the digested cellular contents through this tube, not blood. The itching, which is the characteristic symptom, is an allergic reaction to the digestive enzymes and the presence of the stylostome.
Symptoms do not begin immediately but manifest several hours after attachment, often three to six hours later. The resulting lesions are red welts, pimple-like bumps, or sometimes blisters, which may persist for up to two weeks. The chigger feeds for a few days before dropping off naturally, but the irritation continues long after the mite is gone.
Preventing Chigger Exposure and Removing Them
Preventing chigger bites requires creating a barrier between the larvae and the skin. Wearing protective clothing, such as long-sleeved shirts and long pants, reduces the risk of attachment. Tucking pant legs into socks and shirts into pants helps block the chiggers’ path as they crawl upward.
Chemical repellents offer a reliable defense against these mites. Products containing DEET can be applied to exposed skin and clothing. Permethrin is an effective insecticide that should only be applied to clothing, as it kills chiggers upon contact. Applying sulfur powder to socks and pant cuffs is another traditional method used to repel the mites.
If exposure is suspected, immediate action can prevent the larvae from attaching and feeding. Taking a warm, soapy shower and scrubbing the skin vigorously within a few hours of leaving an infested area washes off unattached larvae. For bites that have already begun to itch, over-the-counter anti-itch creams, such as hydrocortisone or calamine lotion, help manage symptoms.