Adults are active during the winter months in the more southern part of their distribution, mating and laying eggs amongst the mosses. Adults of Alaskan species are active during the Spring and Summer months. The greatest species diversity is to be found along the Pacific Coast of North America. Adults have adapted to the colder environment by becoming dark in color, presumably to better absorb the winter sunshine. They also have wings reduced to narrow straps in males and short, rounded stubs in females , presumably to reduce body surface area.
Females also have an elongate, tubular ovipositor .
They have the ability to hop, and some specialists think that they may share a direct ancestral link with fleas.