A Kleptoparasitic Cecidomyiid and Other Flies Associated With Spiders

Spiders and their webs are predictable sources of insect cadavers.A small number of animals regularly exploit this resource, either askleptoparasites or commensals, depending on whether symbiontscompete for the same prey (see Robinson and Robinson, 1977, formore detailed terminology). Among the thieves are specializedspiders (citations in Vollrath 1979a, 1979b), mature male andjuvenile spiders (Stowe 1978, citations in Nyffeler and Benz 1980),Hemiptera (Davis and Russell 1969), a hummingbird (takes webbingin addition to small insects, Young 1971), panorpid scorpion-flies(Thornhill 1975), Lepidoptera larvae (Robinson 1978), wasps(Jeanne 1972), damselflies (Vollrath 1977), and a handful of flies(reviews in Knab 1915; Bristowe 1931, 1941; Lindner 1937; Richards1953; Robinson and Robinson 1977). Only a few of the reports onDiptera kleptoparasites originate from North America (McCook1889, Frost 1913, Downes and Smith 1969). With a single exception(Downes and Smith 1969), all of the previously described kleptoparasiticflies belong to the Brachycera and Cyclorrhapha. Wereport here on a surprisingly diverse kleptoparasitic Diptera faunain north central Florida with a cecidomyiid (Nematocera) as itsdominant member