We read Ellen Hartley’s recent letter with interest and wish to clarify the rationale for managing deer to reduce the risk of tick borne disease. Our studies indeed demonstrate that the source of infection for deer ticks can be diverse, depending on the small animals that may be present. This may differ between sites and years. We find that shrews are underappreciated as contributors to the production of Lyme and even babesia infected ticks. Heretofore researchers, including our own lab, have focused on white footed mice as the dominant source. New methods that we used help to refine our understanding. Science is always self-revising based on new data.
However, it is not correct to suggest that deer have a role in infecting ticks and we have never stated this, nor do any of our scientific colleagues. Lyme disease (and babesiosis, human granulocytic anaplasmosis, Borrelia miyamotoi disease, and Powassan encephalitis) risk is a result of two processes: production of new ticks and infection of those ticks because the ticks are largely born uninfected. Deer are solely responsible for producing new ticks. They do not infect ticks. The adult deer tick feeds on larger animals, never an animal smaller than a housecat or fox. Blood is required for the adult female tick to lay eggs, usually 2,000 eggs apiece. Deer are the most common larger animal in all sites plagued by Lyme disease. Each deer may have hundreds of adult female ticks and we have estimated that a single deer may produce as many as 2 million baby (larval) ticks during each adult deer tick activity season (October-May).
Deer produce the deer ticks and diverse small animals infect the ticks. One might make a chicken or the egg argument, but if there were fewer ticks being produced, there would be fewer infections among the small animals. Reducing deer or treating them with insecticides has greatly reduced tick abundance in numerous studies. When done as part of an integrated tick management program, with personal protection (permethrin treated clothing, particularly socks) and habitat management and judicious use of broadcast insecticides, we can reduce tick bites and the risk of tick borne disease.
Deer reduction is badly needed on Martha’s Vineyard, and if the risk of Lyme disease is not sufficient reason to do this, the new and expanding threat of alpha-gal allergy is more reason. Deer produce lone star ticks. The female lone star tick feeds only on deer on Martha’s Vineyard. Each fed female may lay as many as 3,500 eggs. Lone star ticks are responsible for alpha gal.
We applaud the recent efforts by TickFreeMV, the Massachusetts Division of Fish and Wildlife, Patrick Roden-Reynolds, Dick Johnson and Lea Hamner in trying to manage deer more effectively out there. This important initiative will make the Vineyard a better place for all of our children and their children.
Sam Telford and Heidi Goethert
Tufts University
This article appears in May 22, 2026.