Follow Facebook for any length of time and you will likely see a meme about opossums and ticks. Just visit the Facebook page, Opossum Awareness & Advocacy for examples. Opossums (Didelphis virginiana) are the only native marsupial in North America. Opossum boosters, i.e. those who tout the virtues of opossums, claim that opossums are tick killers extraordinaire. A listener to my vodcast, Living the Wild Life, part of the Pest Geek Podcast family, asked me to write about whether opossums kill ticks. Thus this blog post.
Opossums are host to ticks
In performing my research, it became quickly apparent that opossums are host to a variety of ticks (See Dryden, M. W. and P.A. Payne. 2004. Biology and Control of Ticks Infesting Dogs and Cats in North America. Veterinary Therapeutics 5:2(Summer):139-154)). The authors list no less than 4 ticks that commonly infest opossums. So, at first glance, it does seem strange that if opossums are such good killers of ticks, why are opossums not killing the ticks resident on their own bodies? Granted, such an argument is not a conclusive one against opossums being tick killers because perhaps the ticks are in locations where the opossum can’t reach.
Opossums as Traps for Ticks
Keesing, F, J. Brunner et al. in a 2009 article titled, “Hosts as ecological traps for the vector of Lyme disease” published in the Proceedings of the Royal Society. 276:3911-3919 say that opossums kill 83-96% of the ticks that attempt to parasitize them. Keesing and Brunner (2009) continue on this subject by noting that opossums in upstate New York average 199 larval ticks on their bodies during peak larval tick season. Working backward, they surmised, that if a captured opossum had 199 ticks on them and given that opossums removed approximately 97% of the ticks from their bodies, then the opossum had to have originally hosted 5,500 larval ticks in order to be left with 199 larval ticks when the opossum was found. Thus, opossums were removing ticks from the environment by removing the ticks that got on them.
If true, that’s pretty remarkable as it would suggest that opossums reduce the number of ticks in the habitat. But there are several questions that need to be addressed. First, working backwards from what one sees to imagine what took place previously is certainly logical but nevertheless, still lacks empirical proof. Saying they eat 5,500 ticks is different than showing they eat 5,500 ticks. Second, let’s assume opossums do eat 5,500 ticks per year. Does this feeding behavior reduce the number of ticks in the environment or would the ticks have died anyway? We often forget that many insects never complete their lifecycle. Third, as a video by Snopes.com argued that even if opossums killed ticks it is unknown whether such feeding reduces the prevalence of Lyme disease.
Bottom Line
Do opossums eat ticks? Yes. But as Francis Skalicky of the Missouri Department of Conservation writes https://www.news-leader.com/story/sports/outdoors/2019/02/22/opossums-more-intriguing-people-realize/2907466002/ it may be better to say that ticks consume ticks rather than eat because opossums are not targeting ticks in the environment to feed on. Rather they groom themselves and eat the ticks they find. Are opossums the major tick killers that will reduce Lyme disease? Probably not, but who knows where research might lead?
Stephen M. Vantassel, CWCP, ACE, is the owner of Wildlife Control Consultant, LLC. He helps people restore their balance with nature through publishing, training, consulting, and the internet. He has published numerous articles in trade and academic publications available at {Stephen’s Academia.edu Page} along with several books {WCC Store}). Listen to his podcast “Living the Wild Life” at {Pest Geek Podcast}. Please subscribe to {Stephen’s YouTube Channel} He is a sought after speaker and trainer. If you would like to have Stephen speak at your event or use his consultation services, send an e-mail to wildlifecontrolconsultant@gmail.com. Copyright All postings are the property of Stephen M. Vantassel and Wildlife Control Consultant, LLC. Text (not images) may be reprinted in non-profit publications provided that the author and website URL is included. If images wish to be used, explicit and written permission must be obtained from Wildlife Control Consultant, LLC.
