By Blake Jackson
The first eastern tent caterpillars (ETC) of the season have begun emerging in Kentucky. Initial sightings were reported in Fayette County, and entomologists at the University of Kentucky Martin-Gatton College of Agriculture, Food and Environment indicate that hatching is now occurring across the state. Typically, egg hatch coincides with the blooming of forsythia and the emergence of Eastern redbud flowers.
ETCs became widely known during the early 2000s when accidental ingestion by pregnant mares was linked to Mare Reproductive Loss Syndrome (MRLS). From 1999 to 2001, MRLS resulted in an estimated 3,500 foal losses, including abortions, stillbirths, and neonatal deaths.
In central Kentucky, around 30% of the 2001-2002 Thoroughbred foal crop was affected, causing a statewide economic impact of approximately $336 million, making ETC management critical for horse owners even today.
Temperature strongly influences ETC development. “The eastern tent caterpillar is one of our early riser pests,” said Jonathan Larson, UK Extension entomologist in the Department of Entomology.
“They overwinter as eggs and begin hatching around 100 growing degree days, a measurement of development for insects that reflects the high and low temperature of any given day.”
ETCs primarily feed on wild cherry, apple, and crabapple trees but may also appear on maple, peach, pear, hawthorn, cherry, and plum. As caterpillars grow to 2–2.5 inches, they often leave host trees in search of additional food or places to pupate, potentially entering pastures.
“Right now, caterpillars are small and their nests won’t be noticeable. Tents will become more obvious over the next 4-6 weeks though. 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,” Larson said.
“The greatest risk occurs when these mature caterpillars leave the trees to pupate and transform into moths. As they travel through the grass, they could be accidentally ingested”
ETCs build compact silk tents in branch crooks, unlike the large, messy webs of fall webworms. Management strategies include keeping mares away from infested trees, removing host trees near paddocks, and, in some cases, applying insecticides like Bacillus Thuringiensis (Bt).
Tall trees may require professional arborists for trunk injections using products such as Tree-äge, Inject-A-Cide B, Abacide 2, or Lepitect, all labeled for horse farms.
Photo Credit: gettyimages-awakr10
Categories: Kentucky, General, Livestock