Indirect evidence for multiple insemination in Chironomus oppositus Walker (Diptera: Chironomidae)

Electrophoretic analysis of an egg mass collected from a natural population of Chironomus oppositus f. whitei, provided indirect evidence that the female had been inseminated by at least 2 different males. This indicates that the previous assumption based on the banding patterns of the polytene chromosomes, that an egg mass is the result of a single mating (Martin et al. 1980), must be treated with caution. Electrophoretic analysis has therefore been able to answer a question on reproductive biology which it is difficult to answer directly or using polytene cytology. The size of the egg mass suggested that it may have been a seond egg mass laid by that female, further suggesting the possibility that a female may re‐mate after she has laid an egg mass.