Eastern Tent Caterpillar Update

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Eastern Tent Caterpillars (ETC) (Malacosoma americanum) caterpillars are accomplished and prolific tent-makers producing highly visible silk nests in the forks of branches.  The nests are now large enough to be easily seen in Greater Cincinnati.  However, at this point in the season, it appears that populations are highly localized and not widespread.


Eastern Tent Caterpillar Early Season Nest


ETC Early Season Nest


The hairy caterpillars prefer to feed on trees in the family Rosaceae, particularly those in the genus Prunus, such as cherries.  They also occasionally feed on ash, birch, maple, and oaks.  The caterpillars are covered in short; grayish-white hairs and they have a distinct, unbroken white stripe down their backs.


ETC Late Season Nest


ETC is capable of causing serious stress to their host trees; newly planted trees are particularly vulnerable.  Leaves lost to caterpillar feeding this spring must be replaced using energy stored from last season.  Small nests can be eliminated digitally using five-fingered "smash and/or smear" techniques.  Less hands-on methods include applications of the naturally occurring bacterium, Bacillus thuringiensis (Bt), applied to early instar stages, as well as standard insecticides labeled for general caterpillar.