Hawkmoth -- flower interactions in the urban landscape: Sphingidae ecology, with a focus on the genus Hemaris

In this dissertation I examined the ecology of moths of the family Sphingidae in New Jersey and elucidated some previously unknown aspects of their behavior as floral visitors. In Chapter 2, I investigated differences in moth abundance and diversity between urban and suburban habitat types. Suburban sites have higher moth abundance and diversity than urban sites. I compared nighttime light intensities across all sites to correlate increased nighttime light intensity with moth abundance and diversity. Urban sites had significantly higher nighttime light intensity, a factor that has been shown to negatively affect the behavior of moths. I analyzed moths’ diets based on pollen grains swabbed from the moths’ bodies. These data were inconclusive due to insufficient sample sizes. In Chapter 3, I examined similar questions regarding diurnal Sphingidae of the genus Hemaris and found that suburban sites had higher moth abundances and diversities than urban sites. I also examined the nectar diets and flight distances of Hemaris moth populations. Pollen grains from purple flowers were significantly more abundant on moths’ bodies across all sites, suggesting a preference for this corolla color. Flight data indicate that Hemaris are vagrants and seldom return to the same patch to feed. In Chapter 4, I examined the foraging behavior of Hemaris compared to the Bombus spp. that they mimic and their Lepidopteran relatives, Papilio glaucus and Manduca rustica. I observed foraging by Hemaris sp., Bombus sp., and P. glaucus at Cirsium discolor, a thistle native to New Jersey. Hemaris individuals visited significantly fewer C. discolor inflorescences and probed significantly fewer C. discolor florets that Bombus or Papilio glaucus. Hemaris do forage more similarly to the related M. rustica than to the other two foragers. Finally, in Chapter 5, I explored Hemaris's visitation to the native Cirsium discolor and non-native Centaurea spp. During the co-blooming period of C. discolor and Centaurea, Hemaris visited significantly more C. discolor inflorescences. Hemaris revert to visiting Centaurea after C. discolor's bloom period ends. C. discolor nectar has a significantly higher sugar concentration than Centaurea nectar so this difference may partially account for Hemaris' higher visitation to C. discolor.