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Horticulture and Home Pest News
Horticulture & Home Pest News is filled with articles on current horticulture, plant care, pest management, and common household pests written by Iowa State University Extension specialists in the Departments of Entomology, Horticulture and Plant Pathology.

Eastern Tent Caterpillar Season Is Upon Us

This article was published originally on 5/12/2010

 
The photo below from Tammy Curley in the Bremer County Extension Office is a reminder that now is the time to look for the silvery-gray webs of the eastern tent caterpillar on apples, crabapples, wild plum, cherry and related trees.  The characteristic silken tents are almost always constructed at the fork of a major branch on the tree or shrub.
 
Caterpillars emerge in late April and early May from eggs that were laid on small twigs last summer by the female moths. During the daytime the caterpillars feed on buds and foliage. On cloudy rainy days and at night the caterpillars remain in the protective confines of the tent. Tents start out very small but enlarge as the caterpillars feed and grow and add to the tents, making them more obvious in the landscape and along roadsides.
 
Damage can be reduced by removing and destroying tents and caterpillars as soon as they are noticed. Tent removal should be done in early morning or late evening or on cool rainy days when the caterpillars are occupying the tents. The caterpillars and the silk webbing are harmless to people; no harm comes from taking down the tent with your bare hands, although I understand some people would rather do this operation with a pole or gloved hands. Foliage sprays of Bacillus thuringiensis can be used if necessary.
 
Eastern tent caterpillar larvae and tent.  Photo by Tammy Curley.Eastern tent caterpillar larvae and tent. Photo by Tammy Curley.