Ticks and Trombicula mites, both of which spend a significant part of their life cycles off their hosts, are most active in warm months. Lice and most mites, on the other hand, spend all their time on the host. The skin surface provides a favourable habitat for these ectoparasites year- round, especially in the winter months when haircoats are thickest and more protection is provided against the drying action of sunlight.