Buckeye Yard and Garden onLine

Joe Boggs reported that Larry Hanks (Pampered Properties LLC., Lexington, KY) provided an early warning by sending images of 1st instar eastern tent caterpillars (Malacosoma americanum) on wild cherry that had hatched from overwintered eggs in Georgetown, KY, late in the day on 3/29, or early in the day on 3/30. ETC egg hatch occurs when accumulated GDD reach 92. As noted above (see Hort Shorts), Cincinnati was at 84 GDD on April 1, so egg hatch is just around the corner in southern Ohio.

Larry's image showed the tiny, hairy caterpillars clustered on the cherry buds in anticipation (hopes) of leaf expansion. In 2001, ETC captured national attention by being linked to Mare Reproductive Loss Syndrome (MRLS). The malady caused widespread loss of thoroughbred foals in Kentucky and cost the industry more than $336 million.

The caterpillars prefer to feed on trees in the family Rosaceae, particularly those in the genus Prunus, such as cherries. They occasionally feed on ash, birch, maple, and oaks. As their name implies, these caterpillars eventually produce very obvious silk tents or nests at limb and branch forks. They live inside the nests, but carouse about the branches of their host tree feeding on expanding foliage. High populations produce rapid defoliation. Since loss of leaves typically occurs early in the season, trees must set out new leaves at considerable energy expense.

If discovered early, the congregated caterpillars can be easily eliminated digitally using "smash and/or smear" techniques. Less hands-on methods include an application of an insecticide, such as Bt (Bacillus thuringiensis) targeting caterpillars while they are still small, or other products labeled for caterpillar control. Numerous predators and parasites also attack this pest, but in some years these agents do not arrive in sufficient numbers to adequately control tent caterpillars.

For more information, see:

• Eastern Tent Caterpillar