Blacklegged Tick



  • Ixodes scapularis
  • Blacklegged tick
  • Deer tick
  • Bear tick


Female: Red/orange with brown dorsal shield

Male: Unremarkable brown with brown dorsal shield, usually smaller than the females

Size: 1\8” as adults, nymphs are as small as the size of a poppy seed or around 1mm.

There are 3 feeding stages of the BLT Larvae, Nymph, and Adult.

  • Larvae appear clear in color and are as tiny as a tip of a sewing needle.
  • Nymphs look like tiny freckles, or poppy seed and resemble adult form but smaller.
  • Adult females are red in color with a black dorsal shield and range in size from a large freckle to size of a tip of a finger when it is engorged.
  • Adult males are indistinct brown with no markings.
  • Each stage requires a blood meal to develop to the next stage. Typically it takes 2-3 years for BLT to complete their life cycle.


Blacklegged tick (BLT) is most common in New England states. It prefers tall grass next to a mixed forest. Beware of fields next to forest, suburban landscapes.

There are 2 feeding seasons: Fall and Spring.

Female Adult ticks that have obtained a blood meal in the fall will lay up to 3,000 eggs into soil or leaf litter before dying. Eggs will take up to 1-2 months to hatch. These larvae will usually feed in May. If an adult female feeds in May eggs will be laid and the resulting larvae will feed around August. Larvae typically feed on small animals including mice and chipmunks.

After feeding, larvae molt into nymphs and seek a second blood meal in the spring. Nymphs are most active during May, June, and July. Nymphs can feed on many different victims including small mammals such as mice and chipmunks as well as, dogs, deer, horses, and humans. 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.

Most human lyme disease results from an undiscovered nymph bite in the summer. In Northern NH, we suspect BLT activity to peak in June and July. Adults BLT that transmit disease can also feed in the fall, but prefer deer and dogs as host.


  • Lyme disease (Borrelia burgdorferi)
  • Anaplasmosis (Anaplasma phagoycytophilum)
  • Babesiosis (Babesia microti)
  • Borrelia miyamotoi
  • Powassan Virus

Learn more about tick-borne diseases on our Diseases Page →


*Data pooled from Bebop Labs and UMass Amherst Lab of Medical Zoology public database , NH 2018. **n represents total # tested ticks for the county. #Precentages of blacklegged ticks (deer ticks) rounded to the nearest percent.