COMPARATIVE SEASONALITY OF VESPULA-GERMANICA (F) AND VESPULA-VULGARIS (L) COLONIES (HYMENOPTERA, VESPIDAE) IN URBAN NELSON, NEW-ZEALAND

Wasp nests reported in Nelson city were studied between 1987 and 1990. More nests were reported in 1989 than any other year. In each year there were at least twice as many common wasp (Vespula vulgaris) as German wasp (V. germanica) nests. New-season common wasp nests had more foragers than German wasp nests in the summer, suggesting earlier successful nest initiation by common wasp queens. The rate of increase in foragers did not vary with species in either 1988 or 1989. Wasp numbers peaked in March and early April. Common wasp nests had more foragers at the peak of the season in 1989 than in 1988 but there was no difference in peak size of German wasp colonies between the two years. Numbers of both species declined sharply in April 1989, but German wasp colonies in 1988 did not decline as much as in 1989, nor as much as common wasp colonies. The number of foragers in overwintered German wasp colonies increased through spring, and one colony had started to decline as early as February. Nests dug up throughout the 1988/89 season contained newly emerged males from early March onwards. Queen cells with eggs or larvae were also present from early March onwards. German wasp colonies initiated the production of the sexual castes earlier in the season than common wasp nests. The overall similarity of the seasonal pattern for German and common wasps means that conventional control strategies should be the same for both species.