PREDATION BY SPIDERS ON GROUND-RELEASED SCREWWORM FLIES, COCHLIOMYIA-HOMINIVORAX (DIPTERA, CALLIPHORIDAE) IN A MOUNTAINOUS AREA OF SOUTHERN MEXICO

Predation by spiders on ground-released adult screwworms, Cochliomyia hominivorax (Coquerel), was studied near Tuxtla Gutierrez, Chiapas, Mexico, during 13 August 1984-23 January 1985. Observations of predatory behavior and manual collections of spiders during September provided the majority of the data. Species in 12 genera of spiders were confirmed as predators of screwworm flies. Nephila clavipes, Eriophora ravilla, Neoscona oaxacensis and Leucauge spp. were the most important predators. Spiders caused an estimated 4.5% mortality to flies in a 2250 m3 area during September. Capture of screwworm flies in webs up to 10 m above ground suggests the need to investigate the importance of forest canopies in screwworm ecology.