Ticks

Characteristics:

Arthropods with a sac-like body ranging from 3-30mmlong. They are the largest Acarines. The head, thoraxand abdomen are closely fused and unsegmented.The body consists of the idiosoma and thegnathosoma (capitulum) with mouthparts consisting ofa pair of chelicerae for cutting the skin of hosts, acentral hypostome (beak) armed with recurved teeth which help to anchor the tick to its host and a pair of sensory palps. The idiosoma is membranous or leathery and sometimes equipped with a scutum (shield). There is one pair of stigmata (eyespot) with a stigmal plate near the legs. Adults are typically eight-legged. There are two major families:

Ixodidae, Hard Ticks.

With a dorsal scutum which covers the whole dorsal surface in males but only developedanteriorly in females to permit distension of the body with blood and eggs. The hind end of thescutum is sometimes grooved. There is a prominent gnathosoma which is visible from above. Thestigmata are situated behind coxae IV. A pulvillus (sticky pad) is situated at the extremity of each leg. Examples are: Brown Dog Tick (Rhipicephalus sanguineus) Hedgehog Tick(Ixodes hexagonus) Castor Bean Tick, Sheep Tick(Ixodes ricinus)

Argasidae, Soft Ticks

No scutum and mouthparts not visible from above. The cuticle is granulated and appearsshrivelled when the tick is starved. The stigmata are usually located between coxae III and IV.There is no pulvillus (sticky pad) on the extremity of each leg. Pigeon Argas (Argas reflexus) Body ca 4.0mm long with granulations and small discs. Thin margin around idiosoma flexedupwards with striations on margin.