Ilus. 21 ref. Sum. (En)

A comparison of larvae and pupae of cacao-associated midges (Diptera:Ceratopogonidae) in various breeding substrates was made between successive rainy and dry seasons in the "Catongo" cacao plantation at Turrialba, Costa Rica. One collection of adult midges on cacao flowers was also made in the rainy season. One cluster of 25 larvae of Forcipomyia fuliginosa (Meigen) was found in one of 22 leaf litter-filled plastic cups in cacao trees in the rainy season, and several pupae of F. cinctipes group were collected from rotten slices of banana tree trunk at this time. A total of five adults fo F. genualis (Loew) emerged from about 25 percent of the leaf litter collected in the rainy season. During the dry season, a few slices of banana tree trunks yielded pupae belonging to F. genualis and F. cinctipes group. Adult midges collected from cacao flowers in the rainy season included Dasyhelea soriai Wirth and Waugh. Although only small portions of available breeding substrate materials were occupied by midges in both seasons, immature stages appeared to be more concentrated in the rotting slices of banana tree trunks during the dry season, a time when flowering in cacao is quite low at this locality. Midge populations appear to be more evenly dispersed within the plantation during the rainy season, a time of peak flowering in cacao. These data, while limited, may reflect general patterns of response to tropical seasonal conditions by cacao-associated midges, some of which might be effective pollinators of cacao. The midge species studied deserve further attention in terms of their possible roles as effective pollinators of T. cacao.