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Defoliating spring caterpillars

This spring you may have noticed caterpillars creeping across your walkway or clustered on the trunks of trees.  You may ask, “Will these caterpillars kill my favorite shade tree?”  The answer is “no”.  Many native caterpillars leave their host trees when they are finished growing.  They are most often looking for a protected location to spin their cocoons when they’re on the move.

Forest tent caterpillars and eastern tent caterpillars are native caterpillars that feed on hardwood trees in Georgia.  While they may occasionally cause unsightly damage, the trees will recover.  Both of these caterpillars are from the genus Malacosoma (Lasiocampidae) – the tent caterpillars.  They are generalist caterpillars that feed on a wide variety of hardwood trees and have one generation each year.  Many tent caterpillar species will build communal webs or “tents”.  Tents provide a location for resting, warmth, and protection from predators.

Eastern tent caterpillars build tents in the forks of tree branches.  The size of the tent grows as the caterpillars grow.  Eggs usually hatch about the time that cherry trees begin producing leaves.  Caterpillars may feed up to eight weeks. Eastern tent caterpillars are fuzzy with a yellowish-white stripe along the back and blue/black dots along each side. 

Forest tent caterpillars do not build tents but form silken mats on tree bark. They cluster in groups on the trunk to reduce heat loss in cool spring temperatures, rest, and molt.   Forest tent caterpillars have a blue stripe along each side and yellowish footprint markings along their backs.  While they can cause large outbreaks in forested areas, trees are generally able to survive this defoliation.  Tree health is compromised only when numerous years of defoliation have occurred. Populations will go down over time due to predators, parasites, and environmental factors.

Eastern and forest tent caterpillars do not bite or sting.  Please let them be as they wander around in search of places to pupate.

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