Introduction: Ticks and mites vie with spiders as the arachnid order with the most species. They are world-wide in distribution and are found in nearly every imaginable terrestrial habitat and even some aquatic environments. In a directly measurable sense, they are certain the most economically important since a number of species are either agricultural pests (mites) or are involved in parasitism and the spread of disease (ticks). However, be aware that a great many species are not parasitic.

The study of ticks and mites, acarology, is often considered a separate discipline from the rest of arachnology. For instance, the American Arachnological Society focuses on non-acarine groups. Nevertheless, mites and ticks are certainly arachnids.

Velvet Mite (Trombidiidae)   © Copyright 2001 by Bryan E. Reynolds	A swarm of ixodid ticks Ixodidae (hard ticks) North Dakota, USA © Copyright 2001 by Bryan E. Reynolds	Questing male Dermacentor occidentalis Ixodidae (hard ticks) Riverside, California, USA © Copyright 2006 by Rick Vetter
Female Ixodes pacificus Ixodidae (hard ticks) © Copyright 2006 by Rick Vetter	Male Ixodes pacificus Ixodidae (hard ticks) California, USA © Copyright 2006 by Rick Vetter

modified March 24, 2006