Ticks have four life stages: egg, immature tick (larva and nymph) and adult. Eggs first hatch into larva and a blood meal is required for larva to molt into nymph. Larva can become infected with a disease causing pathogen after feeding on an infected animal host, like a deer mouse. Larva molt into nymphs and another blood meal is required. Nymphs are usually active during the spring and summer months and can spread a disease causing pathogen during feeding. Afterwards, nymphs molt into adults. Adult ticks are most active during the spring and fall months and can also spread a disease causing pathogen.
If you are bitten by a blacklegged tick it does not mean you will get a tick-borne disease. Not all blacklegged ticks are infected with disease causing pathogens. Only nymph and adult stages can transmit infection. And blacklegged ticks often do not start to feed for the first 24 hours after attaching themselves to a host because they are preparing their bodies to significantly expand during feeding. Spread of tick-borne diseases typically require a minimum attachment time of at least 24 hours.
The risk of a blacklegged tick bite starts when the weather warms up in the spring and continues until the fall until the first permanent snowfall. Blacklegged ticks are usually found within and along the edges of wooded or forested areas, and in areas with woody shrubs and vegetation like tall grasses. They are less likely to be found in open grasslands, agricultural lands, bogs, and wetlands. Blacklegged ticks cannot jump or fly. They climb on vegetation like grasses or shrubs and wait for an animal host. When an animal brushes against the vegetation, they climb onto the host’s body and eventually attempt to attach and feed.
Blacklegged ticks feed by attaching their mouth parts to the skin of an animal (including humans) and drinking blood very slowly over a period of days. A tick bite is generally painless. As ticks feed, their bodies expand to accommodate the blood meal. This is called engorgement. If a blacklegged tick is infected with a tick-borne disease, it can pass this infection to its host during feeding.