CENTRAL ILLINOIS (WCIA) — Veterinarians and zoologists at the University of Illinois are warning owners of bearded dragons about a danger looming this summer for their pets: lightning bugs.

Dr. Krista Keller, a board-certified specialist in zoological medicine at U of I’s Veterinary Teaching Hospital, said in a College of Veterinary Medicine news release that eating a single one of these bugs can be deadly to these animals.

“Lightning bugs, sometimes called fireflies, are fascinating beetles that emit light to attract mates. They are a staple in the backyards in Illinois in the spring and summer months and are fascinating for humans and animals alike,” Keller said. “However, even though many lizard species thrive on a diet composed of insects, these light-emitting bugs are toxic and should never be fed to reptiles or amphibians.“

Keller went on to explain that that lightning bugs contain toxins called lucibufagins, which are toxic to bearded dragons’ heart muscle and will cause death. She added that toxicity from lightning bugs has been reported in other lizard species as well.

For bearded dragons, the list of dangerous insects goes beyond just lightning bugs.

“Although bearded dragons and many other lizards eat insects as part of their diet, many insects in our backyards may be toxic or may carry toxic pesticides within their body,” Keller said. “For example, tomato hornworms in the wild are toxic. This can be very confusing when you go to your pet store and see this species sold as food for your insect-loving beardie or chameleon. The ones at the store are highly cultivated and safe for pets, but hornworms from your backyard feed on plants that contain toxins and those toxins accumulate in the insects. Feeding these wild-caught insects to your reptile will pass the toxins to your pet.”

Keller said that it is healthy for bearded dragons to spend time outside, but owners should closely monitor them to ensure they aren’t eating wild bugs. It’s also important, she said, that owners consult with their veterinarian to make sure pets are getting an appropriate and balanced diet.

“Although your beardie will enjoy being outside, do not allow it outside during twilight hours when lightning bugs are active,” Keller advised. “It may not be able to resist a bright lightning bug if it sees one.”

If a bearded dragon or lizard pet has accidentally eaten a lightning bug, owners are advised to get them emergency veterinary care immediately. Keller also recommended getting regular checkups, which establish both the pets’ health and a relationship between owner and veterinarian.