Sweetgum Defoliator Caterpillars: A Rare but Harmless Outbreak

Small black pellets (frass) falling from sweetgum trees, along with thinning crowns, indicate an infestation of sweetgum defoliator caterpillars (Paectes abrostoloides). This native moth lays eggs in early summer; the caterpillars feed for several weeks before pupating. The last major outbreak in Georgia was in 1977, and natural viruses typically collapse the population within a season.

No control is needed—the trees will releaf, and the caterpillars rarely return in consecutive years. The damage looks alarming but is temporary. Monitor next spring, but expect natural controls to keep numbers low.