The black-legged tick, or the deer tick, is found in the Northeastern and Midwestern regions of the United States. Its scientific name is Ixodes scapularis. This species of tick is known as a vector for several diseases, including Lyme disease. They are a common tick species in Connecticut.

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Habits

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The black-legged tick is often referred to as the deer tick because its preferred warm-blooded host is the whitetail deer. But this tick also feeds on mice and rodents, as well as humans. You can find black-legged ticks in low vegetation, like shrubs and ferns. They sit and wait for a potential host to pass by, latching on when one does.

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Black-legged ticks often cling to fur and clothing and will crawl toward warmer spots on the body where blood is closer to the surface. You can’t feel a bite from a black-legged tick since their saliva contains a numbing anesthetic. Black-legged ticks may spend days gorging on a blood meal from their host. This makes them particularly dangerous, as you may not even notice a tick on you until after the damage is done.

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Black-legged ticks are hardy creatures, able to withstand severe winter temperatures that are common to Connecticut and the Northeast. Typically, these ticks are among the first invertebrates in their environment to become active again in the spring.

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Lifecycle

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Black-legged ticks have a 2-year lifespan, passing through 4 life stages. These are egg, larva, nymph, and adult. Eggs hatch into larvae between spring and summer. In each stage of life, a black-legged tick must have a blood meal from a host. Larvae go out in search of hosts, usually targeting smaller animals like rodents and mice.

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Once the larvae have engorged themselves, they molt and enter the nymph phase the following spring. At this point, they will seek out large and small hosts, including humans. Black-legged ticks are more dangerous in this phase because they are tinier and therefore difficult to spot.

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Finally, the tick enters the adult phase, in which it must feed a third and final time. In this phase, black-legged ticks look for large animals as hosts, where they’re more likely to find mates. After female adult ticks have fed off their host, they will wait out the winter and lay eggs in the spring. For more info on the lifecycle of ticks, check out this video from New York State Integrated Pest Management. https://www.youtube.com/watch?v=k5_5vM5aub4 or this helpful infographic from the CDC. https://www.cdc.gov/ticks/surveillance/

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 Identification

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How can you spot a black-legged tick? They are named for their appearance, so naturally, these arachnids have 8 black legs. Males are usually dark brown, whereas females are more reddish-brown. They have round bodies when they’re not engorged.

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After they’ve had a blood meal, however, an engorged black-legged tick can be unrecognizable from its normal state. It will appear ovular and be gray instead of dark or reddish-brown. To correctly identify a black-legged tick when it’s engorged, look at its legs and upper body, as these remain unchanged.

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After you’ve gone hiking in the forest or walking through brush and tall grass, always check your body for ticks. Ticks hide in warm, secure areas when feeding. So pay extra attention to armpits, elbows, behind the knees, in hair, or behind the neck.

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Bacterium Carried

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Black-legged ticks are vectors for several diseases, including Lyme disease. In fact, this species of tick is the main vector of Lyme disease in North America. The Borrelia burgdorferi bacterium that causes symptoms of Lyme disease is transmitted to ticks in any of their life stages (apart from the egg). A black-legged larva might feed on a rodent that’s infected with the Borrelia species and these pathogens are then absorbed by the tick.

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Black-legged ticks carry these pathogens with them through their lifecycle, although females don’t pass the bacteria on to their eggs. When humans are bitten by a black-legged tick carrying these pathogens, they are susceptible to Lyme disease  (see lyme disease symptoms pictures above). These ticks are also known vectors for babesiosis, anaplasmosis, and Powassan virus disease.

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Summing Up

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The Black-legged tick, as a major vector for Lyme disease, is one of the most dangerous tick species out there. Their prevalence in Connecticut and the Northeast makes them an even greater threat to those living here. Remember to always cover your arms and legs, as well as wear socks and closed-toe shoes when you go out in forestry or tall-grass areas. And always check yourself for ticks when you return.

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Black-legged ticks may be pernicious, but by educating yourself on their potential harm and taking necessary precautions, you can protect yourself.