Mapping European deer ked (Diptera: Hippoboscidae) abundance across Pennsylvania using traditional and citizen science methods

Authors: SKVARLA, MICHAEL - Pennsylvania State University; Poh, Karen; EVANS, JESSE - Pennsylvania State University; MACHTINGER, ERIKA - Pennsylvania State University

Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/29/2026
Publication Date: 6/3/2026
Citation: Skvarla, M.J., Poh, K.C., Evans, J.R., Machtinger, E. 2026. Mapping European deer ked (Diptera: Hippoboscidae) abundance across Pennsylvania using traditional and citizen science methods. Journal of Medical Entomology. 63(3).Article 074. https://doi.org/10.1093/jme/tjag074.
DOI: https://doi.org/10.1093/jme/tjag074

Interpretive Summary: European deer keds are small, blood-sucking flies that typically feed on deer and other hooved wildlife, but they can also bite people These flies were introduced to North America in the late 1800s and have become common in the northeastern U.S., including Pennsylvania. While earlier reports of their presence were general and often based on regional or state-level observations, new studies have started mapping their exact locations more precisely. This research focused on deer ked populations in Pennsylvania to better understand where these flies are most and least abundant. Our findings show that deer keds are most common in northern Pennsylvania, less so in central and western parts of the Commonwealth, and almost absent in the southwestern regions. By mapping where these flies are found, we aim to help educate the public and provide useful information for people to protect themselves from bites, especially in areas where the flies are more abundant.

Technical Abstract: European deer keds (Diptera: Hippoboscidae: Lipoptena cervi (Linnaeus, 1758)) are blood-feeding ectoparasitic flies that usually feed on deer and other cervids but sometimes bite humans. Introduced into North America in the late 1800s, they have since become widespread in the Northeast. European deer keds were historically reported at the regional or state level, but recent work has begun to clarify their range by compiling county-level occurrence data. We expand upon this trend by using multiple methods to determine where deer keds are relatively more and less abundance in Pennsylvania. Based on our results, European deer keds are most abundance in northern Pennsylvania, present but less abundant in central and western Pennsylvania, and absent, or nearly so, from southwestern counties. Understanding where deer keds occur will inform public education and allow the public to better protect themselves from deer ked bites.