Ticks are blood-sucking parasites ofmammals, birds, reptiles, and amphibians. They are closely related to mites, but are distinguished by their body shape and large size. The head, thorax, and abdomen in ticks are fused into a single unit. Males are typically small and may be unnoticed, but females often have an enlarged abdomen that is filled with a recent blood meal or with thousands of eggs. Ticks have seasonal abundance: nymphs and adults actively search for a host in early spring; females usually lay eggs in summer; adults search for a host in fall; and most early-stage nymphs overwinter, and then search for hosts and a blood meal in spring.
The mouthparts of ticks are formed into an elongated organ that projects forward from the front of the head.
This is the portion that is inserted into the skin of the host animal. It has rows of backward-directed spines that hold the tick in place and make it difficult to remove a tick once it starts to feed. Often, this portion of the mouthpart remains in the skin when a tick is removed, but there are no ill effects from this.
Mites are generally oval with no distinct body regions. They are abundant in soil, and many are parasitic on insects and other animals. Others are scavengers on plant and animal matter, and some feed on live plants. There are several species of mites that live in bird nests and feed on the blood of adult and nestling birds. When these nests are abandoned in late spring, or when the nests are disturbed, the mites will move away. Bird nests may be built on window ledges, in the external openings of clothes—dryer vents, or in other locations on the house. When these nests are abandoned, mites may move indoors. They cannot feed on humans, but they can give a mild bite on the skin.
Sowbugs and pillbugs are closely related to lobsters, crayfish, crabs, and shrimps. These animals usually remain on or in damp soil or other moist habitats, and are active at night when humidity is high. They often gather together to reduce body evaporation and maintain water balance. Pillbugs resemble sowbugs, but differ in their body shape and behavior. The pillbug’s abdomen is rounded at the end, but in sowbugs there is a pair of pointed tails at the end of the abdomen. When a pillbug is disturbed, it bends its body head to tail to form a compact ball; sowbugs are not capable of forming a compact ball.