The Effect of Temperature on Fecundity and Longevity of the Black Blow Fly, Phormia regina

Adults of laboratory and wild strains of the black blow fly, Phormia regina (Meigen), were exposed to chilling, subfreezing, and high temperatures for varying periods. At 40 ± 2°F there was a negative correlation between chilling time and oviposition in both strains. Egg production was greater in the laboratory strain and continued over a longer period. Mortality in the wild strain was lower than in the laboratory strain following 7 and 14 days of chilling but was higher following 28 and 35 days of chilling. The wild strain showed a more vigorous response in longevity than the laboratory strain after having been chilled for 7-28 days and exposed to a favorable temperature. The laboratory strain could not withstand exposure to a subfreezing temperature of 8°F for 12 hr, and 100% mortality occurred within 3 days when this strain was exposed to this temperature for 6 hr and then chilled for 10 days. The laboratory strain did not survive exposure to 112°F for 1 hr, but some individuals survived exposure to 100°F for 15 days. These experiments suggest that under natural conditions relatively few black blow fly adults survive long periods of winter temperatures in temperate regions. Methods of rearing and maintaining flies in the laboratory are described.