Invasion and Colonization of Upper Elevations on East Maui (Hawaii) by Vespula pensylvanica (Hymenoptera: Vespidae)

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Abstract
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 ≈20 times larger than annual colonies. Some overwintered colonies undergo at least two distinct episodes of queen cell construction. Evidence is provided in support of two distinct routes to requeening (a likely requirement for successful colony overwintering): outside queens join a colony late in the season, and queens produced within the colony at the end of the first season remain for the second season.