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American Dog Tick (Wood Tick)


The adult American dog tick is a hard tick, 1/8-3/16” long, and reddish-brown with white markings on the back. The mouth is easily seen when viewed from above. The body is flattened and shaped like a teardrop. The female’s shield-like area remains unchanged, but the rest of her body stretches and changes from red-brown to blue-gray as she engorges with blood while feeding. Unlike the adults who have eight legs, the larva is 1/32” long and has six legs and red markings near the eyes. It is pale yellow when unfed turning slate gray and doubles in size when engorged. It molts into an eight-legged nymph that is yellow-brown with red markings near the eyes and 1/16” long when unfed and also doubles in size when engorged with blood.

This tick is a three-host tick, i.e. it requires different and successively larger host animals in order to complete development. It is a very common pest of dogs east of the Rocky Mountains and readily feeds on a variety of other animals including humans. The American dog tick transmits Rocky Mountain spotted fever and can cause tick-induced paralysis if it attaches near the base of the neck.

Larval and nymphal activity begins in March and continues until mid-July. Nymphs are more abundant during the summer period. Adults usually are active in the spring when they are found in “waiting positions” on vegetation along paths and trails. They attach to passing animals, begin to feed, and mate.

The American dog tick does not survive indoors for long and is seldom a problem in structures except when it occasionally falls off an infested dog. It cannot complete its life cycle indoors. If ticks are found inside, most of them can be removed by vacuuming, and the remainder controlled by applying a residual spray or dust in the areas frequented by the dog. Ticks on the pet should be treated on the same day.

Outdoor control of American dog ticks is often necessary Debris and ground cover around the area should be removed to discourage rodent and other small animal activity. Using traps, tracking powders and/or baits should eliminate rodent populations. Cutting high grass and weeds should reduce tick harbourage and questing areas. Barrier sprays and perimeter applications of residual pesticides to all vegetation along paths and trails and grassy areas may be needed in order to reduce the magnitude of the problem.

Individuals who work or spend time in tick-infested areas should protect themselves by wearing light coloured long sleeve shirts and long pants, tucked into their socks and by treating their clothing and skin with repellents. Attached ticks should be carefully removed so that the head is not broken off and left imbedded in the skin.

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