Flower foraging behavior in the nectar feeding moth Hemaris (Lepidoptera: Sphingidae) a mimic of Bombus (Hymenoptera: Apidae)

While the majority of moths in the family Sphingidae are nocturnal, three Eastern North American species are diurnal. These Hemaris species mimic Bombus species in appearance and size and like Bombus are also diurnal in habit. It is established that bees such as Bombus forage primarily within rather than between patches and that large moths spend more time moving between patches and travel longer distances in search of pollen or nectar. Our question was, do Hemaris forage like their Lepidopteran relatives or like the Hymenoptera that they mimic?

From 14-26 August, 2010, I observed a patch of 25 Cirsium discolor flowers. When a pollinator entered the patch, I noted whether the pollinator was Hemaris sp., Bombus sp., or Papilio glaucus. That individual was observed for the duration of its visit to the patch. We counted the number of probes into each C. discolor inflorescence. If the next flower visited was within the patch, the number of probes taken in the inflorescence was recorded. Observations continued until the pollinator exited the patch. This procedure was repeated each time a Hemaris, Bombus, or P. glaucus entered the patch.

Though they mimic Bombus morphologically, Hemaris do not forage in the manner of Bombus or P. glaucus in this system. Hemaris visit significantly fewer flowers per foraging bout than Bombus or P. glaucus, and probe flowers significantly fewer times than either of the other pollinators. Hemaris moths move between flowers quickly, taking few probes in each inflorescence and visiting few inflorescences within the patch.