Chiggers are tiny arachnids, related to spiders and ticks, typically found in grassy or wooded areas. Only their larval stage is parasitic, feeding on a host and causing discomfort.
Understanding Chigger Lifespan
A chigger’s life cycle includes egg, larva, nymph, and adult stages. Adult chiggers overwinter in the soil, emerging in early spring to lay eggs in damp soil or leaf litter. After hatching, the six-legged larvae attach to hosts.
These larvae feed for approximately one to four days on a host before detaching. Once engorged, the larvae drop from the host to the ground, where they transform into nymphs, which possess eight legs. The nymphs then molt through several sub-stages before developing into eight-legged adults. Unlike the parasitic larvae, both nymphs and adults are predatory, feeding on small insects and their eggs found in the soil. Under favorable environmental conditions, the entire life cycle of a chigger can range from about two to twelve months.
Environmental Conditions Leading to Death
Chiggers are highly susceptible to environmental conditions, which play a significant role in their survival and their demise. Temperature is a primary factor; chiggers are most active when ground temperatures are between 77°F and 86°F. They become inactive when temperatures drop below 60°F.
Temperatures below 42°F are lethal for chigger larvae, eggs, and nymphs. Some research indicates that temperatures falling below 47°F are also fatal for these stages. Conversely, chiggers also avoid excessively hot conditions, staying away from surfaces hotter than 99°F, such as sun-baked rocks.
Humidity and moisture levels are equally important for chigger survival. These mites thrive in moist, humid environments, which is why they are often found in brushy, grassy, or weedy areas that retain moisture. Low humidity can severely limit their activity, even when temperatures are otherwise favorable. Chiggers are vulnerable to dehydration, prompting them to seek shaded areas with higher humidity. Maintaining short grass and trimmed vegetation can increase soil temperatures and decrease humidity, making areas less hospitable for chiggers. The absence of a suitable host also leads to their death; chigger larvae cannot survive for long without feeding, typically dying within 24 to 48 hours on clothing or within two months indoors if they cannot find a host.
Seasonal Patterns of Chigger Activity
The activity levels and population density of chiggers fluctuate throughout the year, largely dictated by the prevailing environmental conditions. In most regions, chiggers are active from late spring through early fall, with peak activity commonly occurring during the summer months, particularly from May through September. This peak aligns with periods of hot and humid weather, which are ideal for their development and proliferation.
As autumn progresses and temperatures begin to cool, chigger activity naturally decreases. The arrival of the first hard frost or prolonged periods of cold weather significantly reduces their populations, as the lower temperatures are lethal to the larval, nymph, and egg stages. While these stages largely die off during winter in temperate climates, adult chiggers can overwinter by burrowing into the soil, emerging again in the spring to restart the life cycle by laying eggs. In regions with milder winters, chiggers may remain active year-round, demonstrating their adaptability to sustained warm conditions.