We studied 42 species of saprophagous, Neotropical Copestylum (Diptera, Syrphidae) reared from decaying Cactaceae and Agavaceae. Thirty-three species were reared during fieldwork in Bolivia, Costa Rica, Ecuador, Mexico, Peru, and Trinidad from 1998-2007. Nine species came from museum and private collections. Seven were new species. We describe these new species and the third stage larva and/or puparium and breeding sites of 40 species. Not described are two apparent species related to Copestylum apicale (Loew, 1866) reared from Cactaceae. Resolution of their status was beyond the scope of this paper but reference is made to their distinctive larval morphology. Based on early stage characters all reared species can be placed in ten species groups, all but three of which have been recognized previously on the basis of adult characters. A high level of congruence was found between adult and larval characters in terms of these species groups. Eight of the groups appear to be related closely and may represent a monophyletic lineage within Copestylum that has diversified in xeric habitats. Early stage morphology varied within and amongst groups but two trends in functional morphology are recognizable. One trend is towards feeding in watery decay and the other towards feeding in firmer decay. The latter trend is characterized by species that scoop food and use grinding mills in their head skeletons to break it up. They also have armoured thoraces with varying arrangements of sclerotized spicules or stiffened setae for gripping and protection during tunnelling, a short anal segment, and a short posterior breathing tube for protecting the openings. The former trend is characterized by species with opposite and contrasting features. They filter food and have well-developed pre-oral setal filters but they lack grinding mills or only have poorly developed grinding mills. They have reduced thoracic armature, elongate anal segments, and posterior breathing tubes which facilitates simultaneous feeding and respiration. Comparison with 23 Copestylum species reared from bromeliads (Bromeliaceae) suggests a common pattern of diversification in that species groups with the largest body sizes are more specialized.
Surveys in a xerophytic forests association in an Illinois sand area showed that specialized Batesian mimics of stinging bumblebees or wasps are numerous in spring and early summer, generally absent in midsummer, and present but infrequent in late summer. This extends the known occurrence of this sort of seasonal distribution among mimics to a group of mimetic species which are rare or do not occur in the mesophytic forest associations in Illinois which were surveyed by two previous investigators. Our findings support the hypothesis of these previous investigators that some temperate zone Batesian mimics may be selected to avoid the midsummer season when newly fledged, insectivorous birds are abundant and have not yet learned to shun the models which the mimics resemble.
Biosteres melleus (Gahan), Diachasma alloeum (Muesebeck), D. ferrugineum (Gahan), Opius canaliculatus Gahan, O. downesi Gahan (all Braconidae), and an undescribed Psilus sp. (Diapriidae) emerged from puparia of Rhagoletis pomonella (Walsh) collected in Connecticut during 1977 and 1978. Percentage parasitism ranged from 7.9 to 36.8% in flies on hawthorn and from 0.0 to 23.9% in flies on apple. It exceeded 5.0% in only 5 (22.7%) of 22 samples from apple. Higher rates of parasitism usually occurred at sites where other hosts of apple maggot parasitoids probably infested fruits on nearby plants.
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