This tick is commonly known as the dog tick. After copulation, the female Dermacentor variabilis engorge on host blood, greatly expanding in size and then drop off the dog and lay eggs on the ground. The eggs hatch releasing a six-legged, or hexapod, larva which attaches to passing rodents. The larvae may metamorphose to the eight-legged nymphal stage either on the rodent or after dropping onto the ground. The nymphs attach to a dog, moult to the adult stage, and copulate. Because 2 hosts are necessary, this is a two-host tick. Other species of Dermacentor may be either one-host ticks, with the only off-host activity being the laying of eggs by the female, or three-host ticks, with the nymph feeding and dropping off the host before each moult. Since all stages are blood feeding, and have different hosts for each meal, ticks are important vectors of many protozoan, rickettsial, viral and bacterial diseases.

There are also some images of the tick Haemophysalis leporis-palustris which you will see as electron micrographs as part of the demonstration material.

Structures to note include the chelicerae, hypostome, and palps on the head, the basis capituli, scutum, eyes, and festoons on the dorsal surface, and the spiracle, anus and genital opening on the ventral surface.

Dermacentor variabilis mouth parts

Dermacentor variabilis posterior

Haemophysalis leporis-palustris

Haemophysalis leporis-palustris posterior