Ticks are not insects, but rather are more
closely related to spiders, and even more closely related to mites. All of the
several hundred species of ticks feed on the blood of vertebrate animals. Birds and reptiles are plagued by ticks just
as mammals are.
In general, ticks climb to the top of blades
of grass, climb up weeds or brush and wait for a suitable host to walk by. Ticks may remain in this position for days
or weeks, just waiting. This behavior
is called “questing.”
When a host animal does come by, it must
actually brush up against the weed or blade of grass in order for the tick to
scramble aboard. But the briefest of
contact is all that is needed. There is
speculation that the tick is stimulated to a state of awareness by detecting the
higher than normal concentrations of carbon dioxide in the air, caused by the
animal’s breathing. At any rate, once
the tick is aboard, it searches for a suitable place to feed, often making
several “trial” bites before finding a good spot. When a feeding site is located, the tick attaches itself firmly
with the aid of specialized mouthparts and the feeding begins. Chemicals injected by the tick both
anesthetize the wound and keeps the blood form clotting. Ticks may remain on their host for long periods
of time, up to two weeks sometimes, drinking blood all the while.
Lyme
disease is carried by the deer tick, one
of the Ixodes family. This tick, in its larval form, prefers the white
footed
mouse as a host. Deer and birds also act as hosts and long-distance
transportation. White footed mice are a natural reservoir for a spiral
bacteria
that causes lyme disease. The larval tick acquires the spirochete from
the
mouse, the molts into an adult. When the adult tick bites a human or
other
animal, the bacteria can be transmitted. Horses often fall prey to lyme
disease. Early symptoms of lyme disease are vague, but left untreated
can
severely cripple a person.
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