Chiggers, also called red bugs or harvest mites, are the microscopic, six-legged larval stage of certain mites in the arachnid family, making them relatives of spiders and ticks. Only this tiny larval stage attaches to a host, injecting a digestive enzyme that breaks down skin cells for food. This results in the intensely itchy, reddish welts known as chigger bites. While commonly perceived as only a summer problem, the possibility of an encounter during colder months depends entirely on their temperature requirements and survival strategies.
Chigger Activity and Temperature Thresholds
Chigger activity, the period when parasitic larvae actively seek a host, is strongly tied to ambient temperatures. These mites thrive in warm, humid conditions, peaking when the ground temperature is between 77°F and 86°F. This range aligns with late spring through early fall in most temperate climates, establishing summer as the typical chigger season.
The potential for a bite diminishes significantly once temperatures drop below a certain point. Chiggers become largely inactive when the temperature consistently falls below 60°F. This operational threshold causes the larvae to become sluggish and stop seeking hosts.
However, cold weather does not guarantee safety, as an unseasonably warm spell during winter can temporarily reactivate them. If a winter day rises high enough to meet the 60°F activity threshold, overwintering larvae may become mobile for a brief period. True cold is lethal; larvae die completely when temperatures drop and remain below 42°F.
How Chiggers Survive Cold Weather
While the parasitic larval stage cannot tolerate sustained freezing temperatures, the chigger life cycle includes stages adapted for cold weather survival. Larvae that do not find a host before the hard cold sets in generally die. The species survives winter primarily in its later, non-parasitic stages: the nymph and the adult mite.
These eight-legged adults and nymphs burrow into the soil or find shelter beneath leaf litter and protected ground debris. They enter a state of dormancy, known as diapause, allowing them to wait out the cold weather. The soil and leaf litter act as an insulating layer, helping to keep the temperature slightly above freezing in their immediate environment.
In early spring, as the soil warms up, adult females emerge from their overwintering locations to lay eggs in damp soil. These eggs hatch into the new generation of six-legged larvae that will seek a host. This mechanism ensures populations are ready to re-emerge as soon as the weather is consistently warm enough to support their active life stage.
Prevention and Treatment for Off-Season Encounters
Since chiggers can become active during warm winter interludes, prevention remains the best defense, especially when disturbing leaf litter or walking through tall grass. Wearing long pants and long-sleeved shirts creates a barrier between the skin and the mites. Tucking pant legs into socks or boots is an effective tactic to prevent chiggers from reaching the skin.
Applying an insect repellent containing DEET to exposed skin or using clothing pre-treated with permethrin can deter them. After returning inside, promptly taking a warm, soapy shower can wash away any mites that have not yet attached. Vigorously scrubbing the skin with a washcloth may dislodge recently attached chiggers, reducing potential bites.
If bites occur, treatment focuses on relieving the intense itching, which typically begins hours after the mite has attached. Contrary to myths, chiggers do not burrow into the skin, so home remedies like applying nail polish are not effective. Over-the-counter options such as topical corticosteroids, calamine lotion, or oral antihistamines help manage the inflammation and itchiness. Avoiding scratching the bites prevents secondary skin infections.