Flowers of Ipomoea triloba, I. Setifera, I. battatas, and Aniseia martinicensis growing in three areas of disturbed vegetation in Costa Rica were visited by a large number of foraging insects during the dry—season moths of February and March 1967. The commonest foragers collecting pollen or nectar, or both, were bees in the families Anthophoridae, Apidae, Colletidae, and Halictidae. The species of bees varied with the locality and with the species of plant, but an ordered and predictable sequence in groups of foragers was seen throughout the few hours in the morning that the flowers remained open. Each species of bee had a foraging period for a definite portion of the morning, and the peak activity was often at a different time for each species of bee, usually in mid—or late morning. The average time of an individual bee visit to a flower varied also, and the longest individual visits were early in the morning in at least four genera. The average number of insect visits to 106 flowers was about 20, but ranged from 1 to 142. These flowers seemed morphologically well suited for cross pollination, and the bees foraging in them doubtless served as effective pollen vectors.