Activity patterns and foraging habits of Ectatomma tuberculatum were studied in nests in cocoa plantations of the Soconusco region, Chiapas, Mexico, in both dry and wet seasons. Most foraging was in cocoa trees. Foraging was mainly nocturnal during the dry season while diurnal foraging was more important in the rainy season. More varied foods were brought to the nest during the rainy season. Out of 936 samples of food material taken to the nest by foraging ants, 64.5% consisted of solids and 35.5% of liquids, the latter obtained mainly from the extra-floral nectaries of the cocoa, homopterans or fallen fruit. Solid foods were mostly insects belonging to 11 orders, the most frequent being Hymenoptera, Lepidoptera (larvae) and Homoptera. Most of the insect prey were phytophagous, and only a small fraction were entomophagous. These results show that E. tuberculatum can be an important natural control agent of some phytophagous insects that are potential pests of cocoa in this region. Inglés