THE DARKLING BEETLE, small and shy with an understated matte-black carapace, is better known as its adolescent self, the mealworm. Mealworms and their darkling cousins the superworms are popular “live feeders”—food for pet reptiles and amphibians that won’t eat prey that’s already dead. For years, a disconcerting rumor has bounced around the “herp” (as in, herpetofauna) community. Heed the words of Fishguy2727, posting on Aquaticcommunity.com: “I have talked to a number of people who have FIRST-HAND watched with their own eyes as the animal ate a mealworm, . . . and within ten to twenty seconds the mealworm is chewing out of the animal’s stomach.”
I heard about the phenomenon SECONDHAND from wildlife biologist Tom Pitchford. The mealworm came to mind when I asked Tom whether he knew of any nonparasitic creature that could survive in a stomach for any length of time. He had heard that some online herp forums recommend crushing mealworms’ heads prior to serving. “While the insect is in its death throes, the lizard will come over and eat it.”
Mealworm ranchers scoff. “This is an old wives tale,” says Wormman.com. The owner of Bassetts Cricket (and mealworm) Ranch told me that a slice of carrot, for a mealworm, is a two-day project. “They can’t eat out,” he said. (Though obviously enough people worry about it that it has its own verb form.) But mealworm sellers have a financial stake in the matter. What do reptile and amphibian dealers say? Carlos Haslam, manager of the East Bay Vivarium, a reptile and amphibian store not far from my home, told me that in his forty years in the business, he has not seen the phenomenon nor heard a customer report it happening. He pointed out that lizards chew their food before swallowing. Frogs don’t, but lizards do. And most of the stories are about lizards. Fishguy2727 takes no comfort. “Just because 1,000 people have not had it happen to them does not mean it is impossible. There is no doubt that this can happen.”
As so often is the case with apocryphal tales like this, finding someone who knows someone who’s seen it is easy. Less easy is tracking down an actual eyewitness. One who claims to have seen is John Gray, the animal care technician at the Tracy Laboratory at the University of Nevada, Reno. His boss, Richard Tracy, is a physiological ecologist. He predicts hotspots of future extinction, with reptiles and amphibians as his focus. Eighteen lizards, forty toads, and fifty frogs are under John Gray’s care, but he has not seen it happen to any of them. It happened to a fence lizard he caught in his backyard as a twelve-year-old. He recalls feeding a superworm to his new pet in the evening, and finding the lizard dead the next morning with the superworm “hanging out of its side.”
Tracy is skeptical. He has a theory that the story took root in the public’s consciousness with the 1979 release of Alien, a film in which the title character hatches inside one of the crew and breaks through the skin of the man’s abdomen during a meeting. He questions Gray’s memory. Who can recall, with dependable accuracy, the details of an event that happened thirty years ago? One of the mealworm’s natural behaviors is to crawl underneath things. “Mealworms prefer darkness and to have their body in contact with an object,” says the University of Arizona Darkling Beetle/Mealworm Information sheet, under the heading “Interesting Behaviors.” The sheet’s authors make no mention of mealworms eating their way out of stomachs, which would, you’d think, qualify as interesting behavior. As with the post-laxative stomach slug and snake sightings of yesteryear, it seems more likely that the worm was already on the scene, seeking darkness and framed by happenstance.
However, like most people who work with captive reptiles and amphibians, Tracy has trouble completely dismissing the stories. He’s going to do what experimental biologists do in situations like this: experiment.
PROFESSOR TRACY HAS borrowed an endoscope. It is slimmer than most because it was designed to look up urethras. The scope belonged to a urologist whose daughter studied tortoises at the University of Nevada. He lent it to her to look inside tortoise burrows, and she has lent it to Tracy to watch mealworms inside stomachs. What goes around comes around, and up and in and through.