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 as kleptoparasites or commensals, depending on whether symbionts compete for the same prey (see Robinson and Robinson, 1977, for more detailed terminology). Among the thieves are specialized spiders (citations in Vollrath 1979a, 1979b), mature male and juvenile spiders (Stowe 1978, citations in Nyffeler and Benz 1980), Hemiptera (Davis and Russell 1969), a hummingbird (takes webbing in 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; Richards 1953; Robinson and Robinson 1977). Only a few of the reports on Diptera kleptoparasites originate from North America (McCook 1889, Frost 1913, Downes and Smith 1969). With a single exception (Downes and Smith 1969), all of the previously described kleptoparasitic flies belong to the Brachycera and Cyclorrhapha. We
report here on a surprisingly diverse kleptoparasitic Diptera fauna in north central Florida with a cecidomyiid (Nematocera) as its dominant member.