Comparative phenology and cohort survival of beech scale (Hemiptera: Eriococcidae) in Part of its Native Range (Caucasus Mountains, Georgia) and in an Invaded Area (Massachusetts, USA)

Abstract

The phenology and survival of beech scale, Cryptococcus fagisuga Lindinger (Hemiptera: Eriococcidae), were investigated in part of its native range (Caucasus Mountains, Georgia) and in an invaded area (Massachusetts, USA). Despite nearly identical growing seasons (as measured by cumulative day-degrees), the scale was found to be bivoltine in the Caucasus Mountain region but univoltine in Massachusetts. In Georgia, scales overwintered as adults, whereas in Massachusetts, 1st instar crawlers were the overwintering stage. In Massachusetts, protective cages increased scale survival over a year-long period, but the effect was not great and was presumed to be due to exclusion of generalist predators, not specialized natural enemies. There was no effect of caging on survival in Georgia, and no support was found for the hypothesis that specialized natural enemies might exist in the scale's native range that might be imported for biological control of the pest in the United States. Rather, it appears that selection for resistance in American beech (Fagus grandifolia Ehrhart; Fagales: Fagaceae) may offer the best chance to restore healthy stands of American beech in North American forests.