Movement patterns of a clear-wing hawkmoth,Hemaris fuciformis,foraging at red catchfly,Viscaria vulgaris

Summary The bee hawkmoth, Hemaris fuciformis, tended to fly in the same direction between successive visits to inflorescences of Viscaria vulgaris. Upon leaving an inflorescence it did not fly to the first inflorescence in its path, but to the second. At inflorescences, the number of animals that started probing decreased from the bottom to the top. These movement patterns probably serve to reduce the risk of revisiting flowers. The movements of the moths at inflorescences with 2 flowers per tier were investigated and related to the nectar distribution. The nectar is distributed according to a bonanza-blank pattern, flowers being either empty or full, probably because previous visitors have emptied some, but not all, flowers. It is shown that the two flowers of a tier more often than random belong to the category: blank-bonanza. Thus, if a blank is found, the animal should move sideways to the second flower at the same tier in order to find a bonanza. The flowers of the inflorescences tend to be arranged in vertical rows, and it is shown that two flowers, one above the other, more often than random belong to the two categories: blank-blank or bonanza-bonanza. Thus, if a bonanza is found, the animal should move up to the flower above, in order to find another bonanza. Rules of movement at inflorescences and a rule of departure are proposed based on the probability distribution of the nectar. The observed movements agree quite well with the predicted ones.