tick


tick

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Cattle tick (Boophilus)—E.R. Degginger/EB Inc.

Any of some 825 parasitic arachnid species (suborder Ixodida, order Parasitiformes), found worldwide. Adults may be slightly more than an inch (30 mm) long, but most species are much smaller. Hard ticks start and end each developmental stage—egg, larva, nymph, adult—on the ground; at the completion of each stage, they attach to a host (usually a mammal), engorge on blood, then drop to the ground. Soft ticks feed intermittently, pass through several nymphal stages, and live in the host's den or nest. Hard ticks may draw large amounts of blood, secrete paralyzing or lethal neurotoxins, and transmit diseases. Soft ticks may also carry diseases. The deer tick is the principal vector of Lyme disease.

This entry comes from Encyclopædia Britannica Concise.
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