Deer Support Deer Ticks
Deer are critical to the tick's life cycle since they are the primary source of the blood that will nourish egg development in mated female deer ticks.
Deer don’t infect deer ticks; in fact, they reduce the infection in ticks feeding on them.
Ticks become infected when tick larvae and nymphs feed on mice, chipmunks, red squirrels and other small mammals that are reservoirs of several agents that cause diseases in human and domestic animals.
Above: A tick ovipositing (laying eggs).
Having survived the winter, engorged female deer ticks will generate up to 3000 eggs as warm weather returns. In southern Maine, these are deposited in late May and during the first weeks of June. Larvae will start to be hatched in early August.
Name: This tick’s scientific name is Ixodes scapularus (dammini). Its official common name is black-legged tick, but it is familiarly known as the deer tick, because of its preferred adult-stage host (the animal on which the adult tick typically lives).
Shown below, from left to right: a larva, nymph, adult male and female.
Diseases it can transmit: Lyme disease, anaplasmosis, babesiosis, deer tick virus encephalitis, and a relapsing fever illness caused by a different spirochete (a spiral-shaped bacteria), Borrelia myamotoi.
Where it's found: In Maine, since its first appearance in southern counties in the 1980s, this tick advanced along the coast and then inland, and may now occasionally be encountered in northern Maine. It is commonly found in mixed forests and along the woodland edges of fields and suburban landscapes. Nationally it is found and transmits tick-borne disease throughout northeast and in north-central states. It is present in the south, but because it feeds primarily on non-infectious hosts there, Lyme disease is far less common. A similar tick, Ixodes pacificus, transmits Lyme disease along the Pacific coast.
Life cycle: A mated adult female deer tick, having obtained a blood meal from a white-tailed deer, dog, cat, or other large mammal in the fall or early spring, may deposit up to 3,000 eggs in late May and early June.
Uninfected larvae emerge in mid-summer and soon seek a blood meal, primarily from mice, other small mammals and certain songbirds. Many of the animals they feed on, particularly mice and chipmunks, will have been previously infected with Lyme and other tick-borne diseases; it is from these "reservoir hosts" that deer ticks become infected.
After over-wintering, larvae molt to nymphs which seek a second blood meal in the spring, passing on the infections they acquired as larvae to the next year's crop of small mammal/avian hosts.
Nymphs also feed on humans, dogs, and horses, and other hosts. Their tiny size and painless bites may allow them to remain undetected through the approximately 36 hours it takes for the infection to be transmitted from a feeding tick. Once they've had their fill of blood, deer tick nymphs drop to the leaf litter, and in early fall molt to adult males and females.
Note: Most human Lyme disease results from the bite of undiscovered nymphs in the summer. In Maine, nymphs peak in late June and July, which is when approximately 65% of the human cases of Lyme disease are reported. Dogs and other domestic animals are more frequently infected in the fall and spring by adult ticks which escape detection.