The Prevalence of Introduced Vespula vulgaris Wasps in a New- Zealand Beech Forest Community

In honeydew beech forest in the South Island of New Zealand, introduced Vespula vulgaris wasps are now very abundant. Approximated biomass estimates indicate that Vespula (mostly V. vulgaris) biomass (mean estimate at peak = 3761 g ha-1, averaged over the year = 1097 g ha-1) is as great as, or greater than combined biomasses of birds (best estimate = 206 g ha-1), rodents (up to 914 g ha-1 in some years, but usually much lower) and stoats (up to 30 g ha-1). Relative V. vulgaris biomass is also estimated to be two orders of magnitude greater than native wasp biomass during the peak V. vulgaris season in one beech forest. Mean density of Vespula workers at the peak of the season was estimated to be 10,000 workers ha-1, a greater density than the densities attained by other large wasp species when they have been used (with some success) at 'enhanced densities' as biological control agents overseas. The biological impacts of Vespula, and particularly V. vulgaris, in honeydew beech forest are likely to be great, but most of these impacts have not been documented.