Phenology of Oligolectic Bees andFavorite Flowers

Authors who have discussed this subject have made no systematic phenological observations on bees or on flowers.Referring to the supposed short flight of oligoleges, one says: "Some claim this is so because they are small .Robert- son explains it by saying that the short flight is the result of the visiting of the few closely allied genera of plants.""Both opinions are probably right."Oligolectic bees are not small and their flight averages only 11.8 days shorter than their related polyleges (4, 422).In 2, 71, it is stated that these bees are no smaller than their relatives and the per- centage of small bees is no greater than among the poly- tropes (polyleges).Of local oligoleges, 38 per cent, while of the polyleges 37 per cent, are large.There is no need to explain something which is not a fact.Bees with short flight.Since the female bees do the pollen-collecting, the statements here relate to them.In 1, 30, it is shown that the females of 33 Andrenidee, both poly- lectic and oligolectic, average 48 days and complete their flight in 120 days, March 17-July 14.It was argued that it was advantageous for some of these short-flying bees to fall into 11 sets with non-competitive pollen-collecting habits.Polylectic Andrenidm average only 7.7 days longer than the oligoleges (4, 427).Oligolectic bees resemble their relatives in time even more than they resemble the plants on which they depend (3, 108).The percentages of bees flying simul- taneously, May-September, are from 45.9 to 47.2 (5, 522).Short flights make it possible for the bees to be distributed so that not more than 47.2 per cent are flying at the same time (3, 107).This, I think, shows the principal advantages of a short flight.