EFFECTS OF LARVAL CROWDING ON SIZE AND FECUNDITY OF THE BLOW FLY, CALLIPHORA-VICINA (DIPTERA, CALLIPHORIDAE)

Increased crowding of larvae of the blow fly, Cailiphora vicina, withi n a standard quantity of meat led to reduced larval and puparial weigh t, shortened development, reduced adult size, and lowered fecundity. A pparent ''critical weights'' for pupariation in overcrowded cultures w ere lower than those for larvae manually extracted from under-crowded cultures, suggesting that weight per se is not the decisive factor but - within a rather wide size range - a period of feeding after the mou lt to the third instar is necessary for onward development to the next instar.