COLD-HARDINESS IN FALL AND WINTER ADULTS OF THE SOCIAL WASP POLISTES FUSCATUS (HYMENOPTERA: VESPIDAE) IN SOUTHERN ONTARIO

AbstractCold-hardiness was investigated in fall and winter populations of the social wasp Polistes fuscatus (Fabricius), Individuals collected in the fall were able to survive 48 h at −10 °C. Both sexes were equally capable of surviving −5 °C. However, at −7.5 °C and −10.0 °C, females were more cold-hardy than males. About 50% of the overwintering female population were able to survive temperatures as low as −20 °C and monthly temperature fluctuations as great as 30 °C. None of the overwintering females was able to survive 48 h of −25 °C. Adult females of P. fuscatus are able to survive a winter temperature regime that, because of a combination of large fluctuations and low temperatures, is among the most severe reported for any adult insect.