The University of Kentucky’s Maxwell H. Gluck Equine Research Center has announced that entomologists at the University have received reports of “greater than average” counts of Eastern Tent Caterpillars in some areas of the state and have urged awareness by breeders.
Monitoring the population is significant, as accidental ingestion of this species by pregnant broodmares was linked to a devastating outbreak of Mare Reproductive Loss Syndrome in Kentucky some 25 years ago. From 1999 to 2001, MRLS led to abortions, stillbirths, and neonatal deaths that cost Central Kentucky around 30 percent of its 2001 and 2002 Thoroughbred foal crops, and had a state economic impact of $336 million across all horse breeds.
In the statement reporting the higher counts of caterpillars, the Gluck Center said that “breeders are encouraged to be vigilant over the next month as caterpillars are likely to be moving across pastures from mid-May to early June. Pregnant mares should be moved away from caterpillars during this migration.
“The migration is the normal process as they move from feeding areas to pupate before turning into moths,” the statement continued. “Caterpillars feed primarily on cherry, crabapple, and apple trees and can move 40-100 yards from the tree to pupate. During this movement, pregnant mares may encounter and ingest caterpillars on pasture.”
The University’s entomologists noted that the trees that provide a food source for these caterpillars can be monitored for egg masses – which are hatching later than normal this year due to an extended deep freeze in the winter – and developing nests. Removing affected branches is one preventative measure.
“If farm managers notice high numbers of nests, they should relocate pregnant mares from areas near wild cherry trees to reduce the risk of exposure,” said Jonathan Larson, assistant extension entomology professor. “Understanding their life cycle and habitat preferences allows us to address potential risks preemptively. Awareness is our best defense.”
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