Reproductive Potential and Longevity of Two Relatively Isolated Field Populations of Insecticide-Susceptible House Flies12

Flies collected on two relatively isolated ranches near Ellsworth and Wilmore, Kan., 110 miles apart had virtually no insecticide resistance. Field collections were brought to the laboratory and daily records maintained of eggs laid, longevity, eggs hatched, resulting pupation, and resulting emergence. The Ellsworth f1ies, compared with the Wilmore flies, laid a substantially greater number of eggs earlier in life, except during the second and third days, principally because of (1) a greater number of eggs per female fly-day, but also because of (2) a greater survival of female parents earlier in life. But the Wilmore flies, eventually, almost caught up with the Ellsworth flies in egg production because of a substantially greater production of eggs per female fly-day later in life. Hatchability was less in the Ellsworth population early in life primarily because of a high percentage of hatch of the Wilmore eggs during the second and third days. Hatchability was greater in the Ellsworth flies later in life. Totals for the 27 days of the parents’ lives were not significantly different. Pupation of newly hatched larvae and emergence of pupae were lower in the Ellsworth population during the first two 9-day periods as well as for the entire 27-day period of the parents’ lives. The Ellsworth population produced 24.3 adult offspring per female parent as compared with 49.8 by the Wilmore population, primarily because of the relatively high adult survival, from egg to adult, of Wilmore eggs laid during the (1) second and third days and (2) during the 10- to 18-day period of the lives of the parents, which was when a substantial portion of the Wilmore eggs were produced.