Wednesday, March 26, 2008

Weekly Pest Alert Update


Eastern Tent Caterpillar (Malscosoma americanum)

The ETC commonly emerges when Forsythia is in bloom, or as Cherry buds open in the spring. They emerge from a small metallic egg mass laid on host plant twigs and prefer to feed on the genus Prunus (cherries, sandcherries, other similar fruiting and ornamentals) and Malus (crabapples).

The larvae construct a white web (tent) in the crotch of a branch, leaving the tent to feed during the day on the leaves (leaving the midrib), then returning to the tent in the evening. Full grown caterpillars are 2-2 ½” with a black head and long brownish hairs.
It has a light colored stripe on the back with black, blue, and white spots on the sides of it. Moths are non-descript, and difficult to distinguish between other yellowish-brown moths.

Generally, the ETC is considered an aesthetic pest, because the damage is very early in the year, and the plant quickly adds new leaves after damage, so control is not usually needed. While chemicals can be used to protect fruiting or highly valued trees, removing the tent and disposing of it in a closed bag (preferably later in the day while most caterpillars are in it) is a useful alternative to chemical control.

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