Invasion and colonization of upper elevations on East Maui (Hawaii) by Vespula pensylvanica (Hymenoptera: Vespidae)

The western yellowjacket Vespula pensylvanica (Saussure) has become established on the island of Maui since its initial appearance in 1978. On eastern Maui, colonies show a bimodal elevational distribution with peaks at 600-1,050 m and 2,400-2,700 m. At upper elevations (> 2,000 m) nests occur at disproportionate frequencies beneath Styphelia tameiameiae (Chamisso and Sclechtendal) Mueller bushes. This plant also supports a honeydew-producing mealybug Pseudococcus nudus Ferris, which provides a dietary supplement for adult wasps. On Maui, V. pensylvanica retains its typical annual colony cycle, but in some years colonies overwinter and persist into a second year. Overwintered colonies are approximately equals 20 times larger than annual colonies. Some overwintered colonies undergo at least two distinct episodes of queen cell construction.