The occurrence of paedogenesis in Eristalis larvae (Diptera: Syrphidae).

Paedogenesis is the parthenogenetic reproduction of larvae or pupae of insects. It is rather a rare phenomenon which was first observed in the cecidomyiid genus Miastor and subsequently confirmed (Kahle, 1908, Zoologica 55 : 1–80). The female fly produces 4 or 5 large eggs which hatch into larvae that reproduce paedogenetically, each giving rise to 7–30 daughter larvae, which in turn reproduce in the same manner. It is believed that this procers is repeated for several generations, after which pupation takes place and males and females are produced to give rise, after fertilization, to the paedogenetic cycle over again. Hitherto, the only records dealing with paedogenesis in the larval stage belong to species of Cecidomyiidae and the coleopterous genus Micromalthus (Barber, 1913, Proc. Soc. Ent. Wash. 15 : 31–38; Scott, 1938, Z. Morph. Oekol. Tiere, Berlin 33 : 633–53). There is a doubtful case of its existence in the blow fly Calliphora erythrocephala (Parker, 1922, Psyche 29 : 127–31). Pupal paedogenesis in which pupae are capable of laying eggs which hatch to larvae was recorded in the chironomid Tanytarsus (Zavrel, 1926, Publ. Fac. Sci. Univ. Massaryk, Brno 65 : 1–47) and in the Cecidomyiidae (Wyatt, 1963, Proc. Roy. Ent. Soc. Lond. A 38 : 136–44; 1967, Trans. Roy. Ent. Soc. Lond. 119 : 71–98) and Coleoptera (Barber, 1913, loc. cit.).