The Opossum:

Benefits, Beliefs, Myths & Misconceptions

The Virginia opossum (Didelphis virginiana), commonly known as the North American opossum, or “grinner” in rural dialect, is America’s only marsupial - meaning its young are reared in a pouch. Loosely referred to as a “possum” - the term actually refers to a different species altogether. The opossum is a solitary and nocturnal animal about the size of a domestic cat, holding a blended mix of silver, white, and gray guard hairs which protect an underlying layer of cottony white fur. It is commonly mistaken for a rat in urban settings due to the animal’s hairless tail. The opossum is also characterized by its elongated snout with crocodile-like teeth. The term feigning death - more commonly known as “playing possum” is attributed to the opossum; describing a defense mechanism of the animal when threatened. The animal freezes, curls inward, goes limp, and begins drooling; displaying a sick, wounded animal. A foul odor is emitted from the anal glands to help sell a “diseased and undesirable meal” approach to would-be predators. This reaction isn’t voluntary, but rather brought on through a chemical reaction to danger (like fainting), and can last upwards of 4 hours after being induced. The opossum is a successful opportunist - adapting well to both urban and rural settings and feeding on an array of food sources, which includes human garbage, chickens, insects, carrion, berries, and mast, to name a few.

In recent decades, the opossum has successfully migrated northward - being found in cold climates of the United States once unbeknownst to the animal. At the northern fringes of its range, biologists and trappers can identify the age of individuals based on frostbite of exposed skin extremities - most notably the ears and tail. The animal has traditionally been a staple mid-sized quarry in regions of the American south; both for its edible meat for human consumption, as well as its fur hide.

With regard to suburbanization in the modernized anthropocene, the opossum has reversed overall public opinion in just a few short years. Once regarded as a pest with devilish looks unfavorable in comparison to other charismatic wildlife, the opossum has historically bore the brunt of unwarranted scorn from property owners and city dwellers. However, with new studies focused around the animal’s varied diet as well as an increased disconnect with hunting culture, the opossum has been thrust to the other side of the public opinion spectrum - now being heralded as a species of interest in the environmentalist movement. An increase in popularity in the modern internet-based era comes with many misconceptions. In this section, we explore the benefits and misconceptions over this amazingly adaptable and beneficial furbearer.

The Benefits

Impacts on Lyme Disease

Role as a Public Health Nuisance

Position Statement

The opossum is a highly adaptable forager - taking advantage of whatever seems to be available during their nightly hunts for sustenance. They have been regarded as nature’s clean-up crew - feasting on a myriad of organic matter less desired (or suitable) by other furbearer species. Gardeners tend to encourage the presence of opossums as they feed on detrimental insects such as slugs and foraging beetles, however, the animal is also known to consume fruits and vegetables as well as insects, which may have an adverse effect for a would-be green thumb. They have also been known to feed and forage on young mice and rats, in addition to feeding on dead animals - including some skeletal remains.

Opossums are one of only a few mammalian species less likely to contract the rabies virus. In fact, only 1 in 800 usually contract the disease. This is possibly due to lower body temperatures than most placental mammals, although cases of opossums contracting the disease are documented. They’re also resilient to snake venom, and will actively seek snakes in areas where they are present, according to some reports.

They will also utilize woodchuck and skunk burrows, and can commonly cohabit in these complex den structures with these other mammals. Their reduced odds for transmitting rabies makes them a suitable neighbor for these highly susceptible species.

Lyme disease is an infectious disease caused by the Borrelia bacterium which is spread by certain species of ticks - the black-legged tick (Ixodes scapularis) to be exact. If untreated, symptoms of Lyme may include memory problems and tiredness, loss of mobility in the face, joint pains, severe headaches with neck stiffness, or heart palpitations, among many other symptoms. Repeated episodes of joint pain and swelling may occur for months or years following contraction, which may be accompanied by shooting pains or tingling in the arms and legs. Lyme has become an increasingly common topic in the Northeast United States, including New England (which holds the disease’s title - Old Lyme, Connecticut, for where the disease was first discovered). Due to the cryptic nature of the disease’s symptoms and initial difficulty in diagnosis from the medical field, the disease has been regarded as immense concern for many outdoor enthusiasts, including hikers, hunters, and others who can commonly come into contact with the disease’s host - the black legged tick. Lyme disease is the most common disease spread by ticks in the Northern Hemisphere, and is estimated to affect 300,000 people per year in the United States. Due to its popular hold in current societal culture, especially in the Northeast, topics surrounding Lyme and best practices for mitigation are a constant.

On April 18th 2014, the Cary Institute of Ecosystem Studies and NewsTimes published an article that focused on the role of opossums in the spread of Lyme disease with respect to their role in the ecosystem. The postings referred to the opossum as being a “sort of magnet” for black-legged ticks and related the once infamous marsupial to that of a tick-sucking vacuum. The study contends that opossums are fastidious groomers, most notably with regard to the presence of parasitic blood feeders such as ticks, which attach to host animals to feed on blood. The article, which pulls references from a 2009 study, found that 95% of ticks that latch on to an opossum have the potential to be consumed. In recent years, these findings have been grossly taken out of context by mainstream America with regard to the mitigation and remediation of Lyme Disease. Albeit a dead tick, in any capacity, is typically a good tick! In addition to the findings with a capacity of up to 95% individualized reduction in tick presence on the animal’s body, the study asserted that an opossum has the potential to kill roughly 5,000 ticks in a given season.

The Carry Institute report was, for many years, the most focused record on the relationship between the Opossum and the consumption of ticks. Taking the findings of “up to 5,000 ticks per season” consumed by a foraging opossum into discussion, one must also consider the biology of both species in order to comprehend the dynamics of opossums and Lyme impact.

The blacklegged tick, aka “deer tick” (Ixodes scapularis) is the only species in the northeastern, mid-Atlantic, and north-central United States known to spread Lyme disease. They are most commonly found along the eastern coast of the United States from Florida to Maine and as far west as Texas to the Great Lakes region of the upper Midwest United States. One adult female deer tick can lay as many as 3,000 eggs in the spring of each season. Ticks can only contract Lyme disease if they take a blood meal from an infected host. Since larva have not taken their first blood meal yet, they are unable to have or transmit Lyme disease. Despite the name “deer tick”, deer do not carry Lyme disease – and although deer species do contribute to increasing/spreading tick populations, they do not spread Lyme disease themselves. Of all the wildlife ticks feed upon, only mice, chipmunks, birds and shrews can carry and transmit Lyme disease to a feeding tick. Infected adult female blacklegged ticks cannot pass Lyme disease to their eggs. When a tick takes its first blood meal, it then may become at risk for contracting Lyme disease if the individual animal it feeds from is infected. With only 2-3 blood meals taken in its lifetime, only 2-3 opportunities are allowed for a tick to become infected. If the tick becomes infected during the 1st or 2nd feeding, it can transmit diseases to any animal it feeds on thereafter. (Read more on blacklegged ticks here.)

In contrast, the opossum’s home range varies individually; with factors that include habitat, available food resources, and gender. In general, the opossum’s home range size is thought to be about 12.5 to 38.8 hectares; females generally have a smaller home range. Males are believed to keep larger home ranges due to their reproductive success being contingent on their ability to find mates, whereas female success is based on the accessibility of food items. Virginia opossums were once considered nomadic but research has found that an individual maintains a fairly constant home range throughout their life. (Allen, et al., 1985; Gehrt, et al., 1997; Gipson and Kamler, 2001; Harmon, et al., 2005; McManus, 1974; O'Connell, 2006; Wright, et al., 2012). Additionally, wild opossums average a 2-year lifespan.

While it is noted that the opossum may consume ticks, the Cary Institute study clearly indicates that this is indicative of grooming habits - not a case of opossums actively seeking out ticks on the forest floor. Furthermore, not all tick species found on the opossum are a carrier of Lyme, such as the equally-common American Dog Tick (Dermacentor variabilis).

The notion that opossums actively consume ticks found on their body has been grossly overstated to suggest that the animal is an integral component in the “control” of Lyme disease - a statement that has yet to be proven in any capacity. The idea that opossums consume ticks is vastly different from the misconception that an opossum’s presence on a particular property “prevents” the spread of the disease. The above-mentioned findings would suggest that the opossum’s impact on blacklegged tick consumption is not substantial enough to effectively “control” a localized tick population, thus leaving little evidence that the opossum “controls” the spread and transmission of Lyme disease. Wildlife professionals across the nation tend to echo similar sentiments that nature is far too complex to conclude the opossum is responsible for curbing Lyme transmission.

Dr. Bret Collier, associate professor of wildlife ecology at Louisiana State University’s School of Renewable Natural Resources, takes the misconceptions a step further; contending that ticks are not, in any manner, selected during foraging by Virginia opossums.

He cites the 2021 peer-reviewed paper “Are Virginia opossums really ecological traps for ticks? Groundtruthing laboratory operations,” by Dr. Cecilia Hennessy and Kaitlyn Hild of Eureka College’s Division of Science and Mathematics. Collier notes the 2009 study (the one for which the 2014 Carry Institute report is based upon) looked at captive opossums, while Hennessy and Hild’s later work focused on wild ones - which dives deeper into opossum foraging - to include stomach contents, and scat sampling (as well as 23 scientific papers on the topic). For the 2021 study, Hennessy and Hild used a dissecting microscope to examine the stomachs of 32 Virginia opossums from central Illinois. They found absolutely no evidence of ticks or tick parts and thus concluded that ticks are not a preferred diet item for wild opossums.

“This body of (internet) memes turned out to be an extremely successful advocacy campaign for the opossum; allowing the oft-maligned scavenger to achieve cult status as a bio-control for ticks,” the report concludes. “Unfortunately, these purported benefits are not supported by our findings or by previous diet analyses,” adding that it’s still possible to appreciate opossums in light of the evidence.

This hasn’t quelled the flood of misconceptions to perpetuate, however. Some have taken the Opossum v. Lyme debate a step further, utilizing the animal’s varied diet as yet another indication of its ability to “control” Lyme. Opossums are noted as feeding on mice, which have been proven to be a primary vector for Lyme via the instar stages of blacklegged ticks that latch onto mice. However, similar to their tick consumption, opossums are opportunistic feeders - and no definitive research has determined their diets are comprised primarily of rodents, nor that their feeding on mice has any impact on localized mouse populations to the point of mitigating disease transmission. Similar to foxes and other wildlife, the fact that these animals may on occasion eat mice does not reflect a determination that they “control” the presence of this prey species in any capacity. (Read more regarding predator & prey relationships in our Predator Management section.)

The misconception that the opossum has the capacity to mitigate Lyme spread has taken on a life of its own in popular culture; to the point of raising criticism for the management of the opossum as an abundant species. Many states have bore witness to protests from animal protectionist groups seeking to disband the regulated hunting & trapping of opossums over their new-found tick-consuming fame. These types of knee-jerk, sensationalized demands have the potential to threaten other impacts of the opossum’s abundant presence; which includes their depredation on endangered nesting species such as birds and reptiles. Additionally, demands by homeowners to “hoard” opossums on their property in hopes of a “natural tick control measure” has the capacity to induce public safety issues for the homeowner, children, pets and neighboring properties - not to mention jeopardizing the health and well being of the opossum(s) in question.

The opossum is one of the most popular nuisance wildlife control complaints among citizens - even making national franchise Critter Control’s “most popular calls” list. In states like New Hampshire, the opossum comes in around 80% of complaint calls according to data from 2017’s mandatory WCO reports. The steady ranking is likely due to the opossum’s knack for adapting to urban areas in line with skunks, raccoons and rats - taking advantage of attics, wall voids, garages and crawlspaces in both residential and commercial settings. Some complaints may also pertain to the animal’s odd appearance; complete with a pointy-toothed grin and scaly tail.

The Opossum isn’t as proficient with flea removal as they are with attached ticks - being a big contender in the pest control industry for introducing fleas into suburban dwellings. While occupants may not be aware of a flea presence when the opossum is living in the walls of the home (as a food-host for the fleas), when that animal leaves or dies, the blood feeding fleas still present will seek out the next available food source - which often means humans and their companion animal counterparts (dogs and cats).

Their unsanitary habits - which includes the leaving of scat - creates a public health threat when taken residence in human structures or frequenting common areas such as backyards and public playgrounds where children may come in contact with feces. They also carry a host of potential health issues when their population numbers exceed “tolerated” levels. Los Angeles is one of several cities to feel the brunt of a rat/opossum-induced Typhus Fever outbreak. While a low body core temperature reduces the liklihood of rabies contraction, the opossum is notorious for several other common zoonotic diseases and parasites - such as leptospirosis, tuberculosis, relapsing fever, tularemia, spotted fever, toxoplasmosis, coccidiosis, Chagas disease, and trichomoniasis - just to name a few.

The opossum is well known in the equine industry for their transmission of Equine Protozoal Myeloencephalitis, a disease caused by the apicomplexan parasite Sarcocystis neurona that affects the central nervous system of horses. EPM is contracted by the horse’s ingestion of S neurona sporocysts in feed or water which has been contaminated by opossum waste. The opossum is a definitive host of the disease. Equine owners are encouraged to reduce the chances of opossums gaining access to barns and areas where feed and hay are stored. Experiments have concluded that the protozoon present in EPM can remain viable for a year or more once “dropped” in opossum waste.

The opossum is, in fact, a beneficial and integral furbearer on the North American landscape. The animal’s presence should be profoundly supported and conserved. This notion, however, should not negate the fact that as an abundant and highly adaptable species, the opossum also poses immense public health and social tolerance challenges on a landscape dominated by mankind. As an opportunistic feeder, the opossum’s presence on other species must also be weighed. These challenges require integrated wildlife management protocols to be considered for such a species.

The misconception that opossums are tick “controllers” is deeply rooted in corners of the conservation community today. Its an ideology that may promote potentially detrimental consequences for wildlife conservation if taken wholeheartedly at face value. Furbearer Conservation recognizes that opossums are beneficial and a necessary component of the natural world. We also recognize that these unique marsupials should be regulated and managed for the greater good of natural biodiversity on a human-inhabited continent.

It should be strongly emphasized that we do not necessarily dismiss the regulation of opossum hunting, trapping, and control, outright. Additionally, it is not our intent to necessarily demonize, discredit, or demoralize those in the scientific community who oppose regulated hunting, trapping, and pest control activities. We do, however, wish to establish our immense concern with how the above-mentioned concepts are flaunted to the public as perceived facts, are taken at “face value”, and how they should (or shouldn’t) be applied to ethical wildlife management and conservation procedure for abundant furbearers like opossums. Science is validated with one important factor - context. Science seeks to inform and comprehend understanding. It’s a concept that is independent, and asserts “the chips will fall where they may.” Pseudoscience, by contrast, seeks to scrounge for little bits and pieces of data to correlate and reinforce an agenda, then herald a perceived discovery whether the pieces of the puzzle actually fit together or not.

The Furbearer Conservation project will continue to monitor, research, and advocate for sound science. More importantly, we will criticize pseudoscience and comments derived from misinterpreted data as we see fit, and as it pertains to the ethical, sustainable, and non-biased approach to wildlife management fundamentals. Wildlife management should seek to balance wild species and man’s direct impact, not stack the deck in favor of select species.