The tent caterpillars are on the move. You might encounter a small army of the hairy creatures conducting maneuvers on your deck. Or you could see them squished on the sidewalk.
If you are managing a horse farm, they could be in the pasture grass — not a good thing.
That's because of mare reproductive loss syndrome. In 2001, Kentucky was hit by waves of foal losses. Hundreds of foals were born dead or dying, and thousands of mares aborted in the early stages of pregnancy.
Researchers at the the University of Kentucky tied the mysterious loss to the eastern tent caterpillar. They found that mares were inadvertently eating the caterpillars as they grazed. The hairs on the caterpillars punctured the mares' digestive tract, allowing bacterial infections that caused the abortions and foal deaths.
Because the caterpillars tend to prefer wild cherry, crab apple and apple trees, most farms did away with those trees in their fence rows.
The number of caterpillars each year runs in cycles, and those numbers have slowly crept up since 2001, said Lee Townsend, a UK entomologist.
"I think there's a definite upward trend over Central Kentucky, but it's still spotty," Townsend said Friday. "There are areas where you can drive and see tents pretty commonly. And then there are other areas where they are relatively rare."
UK has been warning horse-farm managers to be on the lookout for caterpillar infestations so they can keep mares away, Townsend said. Although farms eliminated many of the favorite host trees, farm managers need to be on the lookout for those trees in neighbors' fence rows or along roads, he said.
The caterpillars will be leaving their tents for the next week or 10 days. After wandering for a while, they will settle down and spin a cocoon. Moths will emerge in mid- to late June, but they will be barely noticeable, Townsend said.
For homeowners who don't have horses to worry about, the caterpillars are just a nuisance. And there's the yuck factor.
"There's no stinging, there's no toxicity to them," Townsend said. "It's just that most people consider large, hairy worms repulsive ... particularly when there are large numbers of them."