According to Dr. Terry Fitzgerald, the Eastern tent caterpillar does a very good job of detoxifying the cyanide it ingests when eating the leaves of black cherry trees. Fitzgerald, a distinguished university professor of biological sciences at the State University of New York College at Cortland, is an expert on tent caterpillars and their habitats. Researchers at the Gluck Equine Research Center at the University of Kentucky have been working with Fitzgerald because of his knowledge in this area. The professor has studied the Eastern tent caterpillar since 1976.

Fitzgerald explained that these caterpillars detoxify cyanide when it passes through their digestive tracts. “By the time it is a fecal pellet, there isn’t much cyanide left, only a fraction of what was in the leaves,” explained Fitzgerald.

“The image projected that cyanide was raining down out of trees in caterpillar fecal material is not true,” asserted Fitzgerald. “There is some cyanide there (in the feces), but is it enough to cause problems in horses?”

There is up to 4,000 parts per million (ppm) of cyanide in young leaves of black cherry trees that caterpillars prefer to eat, said Fitzgerald. There is 50-100 times less cyanide by weight basis in the fecal pellets than in the leaves