Very little has been published concerning the biology of Pelecinus polyturator. It is the adult females that are most commonly encountered. They are rather slow, elegant fliers, usually seen near the ground. Adults typically emerge in late summer in temperate regions, but may be found throughout the year in the tropics (see graph of temporal distribution). They are typically associated with moist forests or nearby areas. Masner (1995) stated that both males and females may be found resting on mid level vegetation in Costa Rican forests.

Pelecinus was first reported to have been reared from scarab larvae by Forbes (1892; cited in Davis 1919). Since then Petch & Hammond (1926), Hammond (1944), and Lim et al. (1980) have reared the species in the northern part of its range from larvae of Phyllophaga (Coleoptera: Scarabaeidae, Melolonthinae). Lim et al. were able to specify that the host species was P. anxia (Leconte). Muesebeck (1979) also listed P. futilis (Leconte) as a host, but no voucher specimen for this record is stored in the U.S. National Museum of Natural History. Nor have we have found published host records for the tropics. Parasitism rates are low, ranging from approximately 1-3% (Hammond 1944).

Ashmead (1902) commented on the rarity of males in the Nearctic region. Brues (1928) cited this as a possible case of "geographic parthenogenesis," with thelytokous populations in the northern part of the range, and bisexual, arrhenotokous populations in the tropics. He stated further that the tropical populations are smaller in size than the large northern race, and speculated that the unisexual large female "... may quite probably be a tetraploid form...." Young (1990) posed some speculative questions concerning the distribution of males within Wisconsin, among them whether thelytokous parthenogeneis may be related to glaciation.

A number of different color patterns may be found in the wide distribution of Pelecinus. Many of these have been formally described, but current taxonomic opinion recognizes only a single, widespread, and variable species (e.g., Muesebeck 1979, Masner 1993). Muesebeck suggested that careful examination of collections may reveal a complex of species.

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