This paper tries to explain why ants visit the flowers and other reproductive parts of plants inhabiting dry tropical lowlands (in this example, coastal Yucatan, Mexico), and the factors that promote these interactions. The plants adapted to the dry Yucatan coast have structural characteristics to cope with low moisture, the same structures serve also as herbivore deterrents. Thus, during the dry season, some of the most attractive rood sources are the rich tissues of the reproductive structures. The nectar produced by those structures may play an important role, not only in insect nutrition, but in their water balance as well. It is proposed that owing 10 rood shortage during the dry season in coastal Yucatan, ants will rely on the nectar produced on the flowers and other reproductive structures as their main liquid energy source. Twenty-three plant specks arc reported as being visited by ants in coastal Yucatan. Two of these species were studied in more detail: Avicennia germinans, where ants take floral nectar and pollination is not effected, so nectar thievery is taking place; Schomburgkia tibicinis, where ants take circum-floral nectar, and this activity benefits the plant (fewer damaged infloreseences and more matured fruits).