LEXINGTON, Ky. (LEX 18) — It’s hard to believe that the migration patterns of a caterpillar could have a major impact on the horse industry. Both entomologists and equine experts are paying attention to the caterpillar linked to problems with a foal crop more than two decades ago.
Extension entomologist Jonathan Larson, with the University of Kentucky, shared that he was on a drive when something stood out.
“I was traveling on the Bluegrass Parkway, and I saw what I thought was kind of an inordinate amount of nests in trees along the roadside,” he shared.
The nests belonged to eastern tent caterpillars. While they’re native to the region, the caterpillar numbers spike from time to time.
“They do have kind of a boom-and-bust cycle where we see them surge up every 10 years or so,” Larson said. “It is about the right time for that to be occurring.”
Keeping an eye on the cycle is important because these eastern tent caterpillars could impact the horse industry.
“If there's a few around, it's not going to be a big deal. I mean we see them every year,” said Dr. Pete Sheerin, a theriogenologist at Rood & Riddle Equine Hospital. “It's when there's a large number of them and they're overrunning things.”
“They're very hairy caterpillars,” Larson explained. “The current school of thought is that the hairs are sort of irritating to a reproductive mare.”
Sheerin added, “it can cause abortion, fetal death, heart issues, blindness, and so it can have a significant impact on the equine community.”
Members of both the equine and entomology communities believe these caterpillars were a cause of what was labeled in 2001: Mare Reproductive Loss Syndrome. The disease cost the horse industry an estimated $336 million in losses to that year’s foal crop.
“The hospitals were overrun with mares that were having issues, and sick foals and things along that line,” Sheerin recalled.
“These caterpillars seem to be the causative agent,” said Larson. “As they leave the tree and they're ingested by the mares, they can cause this spontaneous abortion to occur.”
Larson explained that eastern tent caterpillars are commonly found in cherry trees, crab orchard trees, and a few other types of trees, and he pointed out to look in areas with a V shape.
“Their nest is kind of a bright white color. It's made of insect silk,” Larson said. “They would be out and about right now making those nests bigger and bigger as they kind of expand them to feed more on different foliage in the tree.”
According to a recent survey sent out to horse owners, just over 40% of respondents said they have noticed more nests on their farms and are taking preventative measures.
“You want to do whatever you can to minimize the horse's exposure to the caterpillars,” Sheerin explained.
“I wouldn't say that we're sending out the alarm fire signal or anything,” Larson added. “It's just something that we want people to be conscientious of so they can protect those mayors and protect those foals.”
You can learn more about identifying and managing eastern tent caterpillars here.
