Be on the lookout! I want all owners of horses, mules and donkeys to know that they should keep their precious animal friends away from trees favored by eastern tent caterpillars! I talked it up with with a few of the University of Missouri Extension specialists, because this is the sort of thing that they do everyday… (and frankly, I eat hay most of the day…)
According to Wayne Bailey, MU Extension entomologist, the eastern tent caterpillar, a native defoliator, typically appears in great numbers after a mild winter and wet spring.
Not only are the gross and creepy and crawling and yucky and… and… and… but they are dangerous too! “When ingested by pregnant mares, these caterpillars can cause mare reproductive loss syndrome (MRLS), which results in the aborting of late-term foal fetuses,” said MU Extension forage specialist Craig Roberts.
Roberts tells me this this is why they are so bad, “The caterpillar’s setae (hairs) are pointy hollow barbs that can penetrate the intestinal walls of the mare and introduce bacteria to susceptible organs, including reproductive organs and amniotic fluids.”
“They can be in water or near water tanks, and horses swallow them as they drink,” Roberts said. “They can be on the ground and consumed during grazing.”
The eastern tent caterpillar is distinguished from other caterpillars by its opulent pearl-white stripe down its back and iridescent blue dots, so be on the lookout! The caterpillars strip trees of their leaves after building a thick web nest or “tent.” They leave the nest when trees leaf out, then migrate to sites such as the sides of trees, debris on the ground, fences or sides of buildings, where they will spin cocoons.
So now that you know all about them… how do you banish them from the barn? There are several ways to manage the pest, Bailey said. Homeowners can simply collect the webbing and worms and burn them. Some might prefer environmentally friendly pesticides such as neem oil or Bt (Bacillus thuringiensis). For large areas or where infestation is intense, over-the-counter options include Sevin, which contains carbaryl. Caterpillar tents are water-repellent, so water-based insecticides will be ineffective.