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Ticks and Rocky Mountain Spotted Fever What are ticks? Ticks are not insects like fleas, flies,and lice, but are arachnids like mites and spiders. They are classified into two families based on their structure. The family Argasidea contains the argasid ticks, which are soft-shelled. Their body lacks a hard shell which is the protective outer covering found on some ticks. The other tick family is named Ixodidae and these ticks possess the hard outer covering, and therefore, are termed hard-shelled ticks. The two hard shelled ticks, Dermacentor andersoni and Dermacentor variabilis are responsible for spreading the organism that causes Rocky Mountain Spotted Fever. All ticks have three pairs of legs during the immature stage and four pairs as an adult. Ticks possess a sensory apparatus called Haller's organ that senses odor, heat and humidity. They use this organ to locate their food source. A tick's diet consists of only blood and ticks require a blood meal to progress to each successive stage in their life. What is the life cycle of ticks? Most ticks are three host ticks. This means that during their development which takes two years, they feed on three different hosts. All ticks have four stages to their life cycle: egg, larvae, nymph, and adult. An example of a life cycle would be to look at the deer tick. Adult female deer ticks lay eggs on the ground in spring. Later in the summer the eggs hatch into larvae (seed ticks). The larvae find an animal ( the first host, which is usually a bird or rodent), live off it's blood for several days, then detach and fall back onto the ground.
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