Arachnids

Arachnids, including spiders, mites, and ticks, have four pairs of jointed legs. Their bodies consist of two parts: the cephalothorax (fused head and thorax); and the abdomen (in some orders, these two parts are also fused). Spiders, mites, and ticks are the most well-known members of this broad group. Of the three large groups (superorders) within the Arachnids, there is one that contains tree pests: Acariformes. There are more than 42,000 described species of Acariformes, but not all of these are plant-feeding. Ticks and their relatives belong to the Parasitiformes, which consist of about 13,000 species.

• Acariformes (mites)