Bug Bites: A Bug Bite Is Not Always a Bug Bite

Ticks are more numerous this year than usual. Probably, the frequent spring rains in much of the state have provided the high moisture and subsequent humidity that ticks need. Ticks are large, flattened mites that feed as parasites on mammals, birds and reptiles. They hatch from eggs into six-legged larvae that locate hosts and feed before dropping off the host and molting into eight-legged nymphs. Nymphs locate hosts, feed and drop off to molt into eight-legged adults. Adults also locate hosts on which to feed. Males may stay on the host, mating with females coming there to feed. Females engorge on blood to several times their original size, drop off the host and lay hundreds of eggs. With each tick having to find three hosts in its lifetime, many ticks starve before reproducing, although ticks can survive for long periods without food.

American dog ticks, commonly known as wood ticks, are the most common in Illinois. They feed as larvae and nymphs on small mammals, only attacking humans when adult. Adults are reddish brown, 3/16 inch long. Females have a silver shield behind the head; males have silver, wiggly lines down the back. These ticks transmit Rocky Mountain spotted fever, a virus found here but most common in North Carolina and nearby areas. In Illinois, they also carry ehrlichiosis, producing symptoms similar to Lyme disease.

Lone star ticks feed on humans and other mammals as larvae, nymphs and adults. Larvae and nymphs are commonly called seed ticks because of their size. Walking through an area of newly hatched larvae may result in hundreds attacking your legs. Adults are about 1/8 inch in diameter, roundish and brown; females have a white spot in the middle of the back.

Blacklegged ticks, including the deer tick subspecies, also feed on people as larvae, nymphs and adults. Larvae are tiny, about the size of the period at the end of a sentence; nymphs are pinhead sized. Both tend to migrate up the legs and feed in the groin area. Adult blacklegged ticks are teardrop-shaped, reddish brown and about 1/8 inch long. The deer tick subspecies is found mainly in the northern half of the United States. Deer tick larvae feed on white-footed mice, picking up the Lyme disease, which can be transmitted to people by the nymphial and adult ticks. In the southern United States, the blacklegged subspecies feed mainly on lizards and birds as immatures and thus do not carry Lyme disease.

Ticks are numerous in areas of tall grass, where humidity is high and hosts common. Mowing greatly reduces tick numbers. When walking or working in areas of tall grass or other areas with ticks, apply a repellent containing about 30% DEET, such as Off or Cutters, to the lower legs and pants legs. If ticks are numerous in mowed areas, spraying carbaryl, sold as Sevin, gives season long control.

If a tick is attached, grasp the head with tweezers where the mouthparts enter the skin, pulling slowly and consistently. The tick will release its mouthparts and come loose. Do not handle the tick. Other methods such as heat and nail polish commonly kill the tick, resulting in locked mouthparts that remain in the wound to cause infection. A tick typically feeds for 24 hours before releasing disease organisms; remove ticks promptly when you find them.

Source: Dr. Philip Nixon, Entomology, University of Illinois

June 2003
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