Manipulation of the length of the sensitive period, and the induction of pupal diapause in the flesh‐fly, Sarcophaga argyrostoma

Larvae of the flesh‐fly Sarcophaga argyrostoma were raised in short‐day cycles ( L D 12 : 12) and at temperatures (18° and 20°C) in which short‐day induction of pupal diapause was less than ‘saturated’. The cultures were then subjected to experimental treatments which modified the duration of larval development (the sensitive period). Overcrowding the larvae within a limited quantity of meat, premature extraction of the third instar larvae from their food, or exposure of the mature larvae to pure CO 2 for 24 h, were all found to accelerate puparium formation, thereby curtailing the sensitive period, and reducing the incidence of pupal diapause. Conversely, lengthening the sensitive period by allowing the mature larvae to wander in wet sawdust increased diapause incidence. The results are interpreted in terms of an interaction between the length of the sensitive period and the ‘required day number’, and also in the light of what is known about the endocrinological control of diapause and development in flesh flies.