The blacklegged tick (Ixodes scapularis) and western blacklegged tick (Ixodes pacificus) are primarily responsible for the transmission of Lyme disease. These ticks are prevalent in the northern United States, as well as along the Pacific Coast.
Blacklegged ticks are hard ticks that are distantly related to both mites and spiders. They are smaller in size than other common ticks and tend to cling to leaves bordering trails. When mammals brush against these leaves, blacklegged ticks attach themselves to their hosts with their front legs.
Blacklegged tick larvae prefer to feed on smaller hosts. They contract infections from small animals during their nymphal stages, which they then pass on to other hosts. Adult blacklegged ticks rarely prefer to feed upon large mammals such as deer or even cattle. Humans bitten by female blacklegged ticks are known as accidental hosts.
These ticks feed by inserting their mouthparts into the skin of the host. If undetected, blacklegged ticks may feed for over a week. Prompt detection is necessary, and medical professional should be consulted if there are medical concerns.