Taming of the Screw, Act Four.

Screwworms are coming to the U.S. and traveling at an alarming rate to get here. In fact, the journey from their one-time prison in Panama is 95% complete. They will come into the U.S.—it’s only a matter of when. Despite their Latin name hominivorax, which means “man eater”, screwworms are much more interested in livestock than they are in you personally. Their hobby is annihilating entire herds of food-producing animals, so if you think grocery prices are high now… just wait. No one wants cheeseburgers to become the new caviar.

But—maybe you will be the one to stop all that. In 2016, the New World Screwworm briefly returned to the Florida Keys. Because everyone here is so unfamiliar with this foreign pest, the invasion went unrecognized for months. It was eventually stamped out but does provide us a prescient glimpse of how events will unfold in the present day. Because we can’t know precisely where or when they’ll strike, we desperately need an army of citizen scientists who can recognize the first New World Screwworm and take decisive action.

To be a citizen scientist (and I did not invent this concept), you need only to care about the greater good and possess a modicum of expertise in your field. NWS can be recognized in wildlife from afar by observing bizarre behavior brought on by pain. You may witness agitated wriggling, obsessive head shaking, rubbing against tree trunks, or standing in water for prolonged periods. The infested wound might be very large and could be visible from a distance. A hunter or pet owner has the best chance at getting close enough to examine the larva itself. Carcasses found along the trail will be chock full of maggots, but those are peaceful decomposers. Do not disturb them. Screwworms, however, feed exclusively on living flesh. They may be observed among the decomposers inhabiting the wound of an injured live animal. Screwworm infestations are intensely painful, while decomposer larvae (remember, they are used in human medicine) create a tickling sensation that the patient may find annoying. NWS can be distinguished from other species by their comparatively large size, their color (becoming more red as they mature), and the way they arrange themselves in an open wound. Decomposer maggots tend to squirm around aimlessly, but carnivorous screwworm larvae orient themselves head down with all their “tails” pointing out, looking a bit like kernels of corn on a cob. Inspecting a single larva reveals dark rings, somewhat resembling the threads of a screw. All the better to burrow with, my dear.

If you think you’ve seen one, don’t delay in reporting it. Your point of contact can be any U.S. veterinarian. Collecting a few larvae would get you the grand prize; samples should be preserved for submission in a small container of ethanol (i.e., hand sanitizer) or rubbing alcohol. It’s disgusting, I know, but just might be worth it to come out of this feeling like a hero, the watchful citizen scientist who spared countless animals a horrible fate and snatched cheeseburgers back from the edge of extinction.

Dr M.S. Regan