University of Wisconsin–Madison

Ixodes scapularis (blacklegged or “deer” tick)

Ixodes scapularis, also known as the blacklegged or deer tick.  This tick is the vector of the bacteria that cause Lyme Disease and Anaplasmosis.  In recent years, the distribution of Ixodes scapularis in Wisconsin has changed dramatically, so that these ticks can now be found in many parts of eastern Wisconsin where they had not been seen before (Lee et al. 2013). In fact, deer ticks are present everywhere in the state where there is forested habitat.

Student teams hit the woods each summer to collect deer tick nymphs and then determine how many are infected.  The map above shows that a range of 11-55% of the nymphs were infected in 2016-17 but the average was about 20%.

Deer ticks have three life stages, the larva becomes a nymph which then becomes an adult.  This takes about 2 years.  Nymphs are of greatest concern, because they are just 2 millimeters (1/10 of an inch) long and are hard to spot and remove quickly.

Above is a blood fed nymph that was attached for 4 days.