What is a deer ked? 



The European deer ked (Lipoptena cervi) is an introduced species of biting fly originally found in Europe, Siberia, and Northern China. Three other deer ked species are native to the southeastern (Neotropical deer ked, Lipoptena mazamae) and western US (Lipoptena depressa and Neolipoptena ferrisi). 

Adult deer keds are 1/8 - 3/16 inches in length. The head, thorax and abdomen are flattened and leathery in appearance.  Deer ked legs are stout with large dark claws. Overall, the ked is covered with strong, dark hairs.

Deer keds are frequently mistaken by hunters as ticks. Keds may superficially resemble ticks but the former are typically larger and highly mobile, often moving rapidly through the hair. Ticks are attached to the skin, do not move around much and are usually found about the head and neck.


Adult deer keds emerge in the fall (mid-September through early November) and immediately fly to a host, which is typically a deer or an elk, and then shed their wings. This enables them to climb unhindered through the hair of the animal. Both male and female keds feed on blood. Deer ked larvae develop inside the mother one at a time. When a larva is fully grown in the mother, it is “born,” falls off the host, and burrows into the forest leaves. The larva then molts into a pupa and waits until the next fall before emerging as an adult to start the cycle over.



Winged deer keds can mistakenly land on and bite humans and dogs in the forest in the fall. Ked bites can be painful and produce small, hard papules at the bite site. In Europe, ked populations can be so high that they are considered a nuisance. After prolonged exposure, people can become sensitized to the bites. Although high deer ked populations have not been reported in the United States, the Penn State Insect Identification Lab has received multiple reports about locally high ked populations in Pennsylvania and New York, so such conditions may exist. In addition to winged keds, deer hunters are at risk of bites from keds coming from harvested deer. Wingless keds frequently crawl from mother deer to fawns, and hunters and veterinarians frequently experience keds crawling from harvested deer up their hands and arms during processing.


A number of recent studies have detected nearly half a dozen disease agents in different deer ked species, including:

  • Cat scratch and related diseases (Bartonella)
  • Lyme disease (Borrelia burgdorferi)
  • Various spotted fevers (Rickettsia spp.)
  • Anaplasmosis (Anaplasma spp.)

Because these studies were based on DNA sequencing, it is unclear if deer keds can transmit disease-causing pathogens or are merely acquiring them by feeding on infected hosts. However, circumstantial evidence suggests that deer keds likely transmit at least some pathogens.