Screwworm's can infest deer, wild turkeys, rabbits, raccoons, livestock even dogs and cats

You’ve probably recently seen TV newscasts on screwworm infestation in livestock. Well, it can also affect live deer, dogs, other small animals, even people in rare cases, says the folks from National Deer Association (NDA). And Pennsylvania deer hunters should be concerned and on the lookout for infected deer.

According to NDA, the tiny New World screwworm (Cochliomyia hominivorax) doesn’t look so frightening until you learn it’s horrific life-cycle. The larvae of this particular fly don’t eat dead tissue like normal maggots. They burrow or “screw” into their victims and eat living flesh of deer. 

New World screwworm kills deer by laying their eggs in open wounds, mucous membranes or orifices of its victims. In spring and summer, newborn fawns are especially susceptible through their umbilical cords. In fall, adult bucks are susceptible through wounds on their heads and necks from fighting other bucks, explains NDA. Once inside the wound or opening, screwworm maggots eat the living tissue and burrow deeper. The wound attracts more flies, which lay additional eggs and the infected wound grows. Without human intervention, secondary infection in the growing wound eventually kills the animal. 

Back in 2016, a screwworm outbreak on Big Pine Key killed nearly 20 percent of Florida’s endangered Key deer population. Florida biologists found living deer with maggot-filled craters on their heads, necks, mouths, genitalia, between their hooves and other locations. 

The screwworm fly originated and escaped South America and made it far north including Mexico and 160 miles south of the Texas border. The impact on livestock activated a response from the U.S. Department of Agriculture where researchers came up with a strategy to defeat the screwworm fly by using radiation to sterilize male screwworm flies and release them by the millions in affected areas. As a result, female flies mated fruitlessly with these sterile males, laid nonviable eggs resulting in a crashed fly population. This was back in 1950s in the Southeast. 

Most recently, active cases of the screwworm fly are in cattle, pigs, horses and dogs in northeast Mexico. The USDA is dispersing 100 million sterile flies per week in Mexico, focusing on areas with detected cases, and it’s dispersing them 50 miles into south Texas as a precaution. 
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It's bad enough we have to deal with Chronic Wasting Disease (CWD) in Pennsylvania deer, now as hunters and animal lovers, we have to be vigilant for screwworm infestation. NDA suggest the biggest thing hunters can do is keep observing deer. NDA says that since hunters aren’t handling deer outside of hunting season, they recommend keeping their trail-cameras out in spring and summer as an aid in keeping an eye on the animals. If spotting a suspected screwworm wound, contact the Pennsylvania Game Commission. As a reminder, they say screwworms attack deer, rabbits, wild turkeys, raccoons and other small mammals which includes livestock, dogs and cats. Symptoms include live maggots in a wound or opening.