Estimates of population size and longevity of adult narcissus bulb fly Merodon equestris Fab. (Diptera: Syrphidae).
Abstract
In investigations on Merodon equestris (F.) infesting daffodils in southern England in 1968-71, daily estimates of adult populations were made using a method described by G.M. Jolly and another described by R.A. Fisher & E.B. Ford. The population trends estimated by the 2 methods generally coincided, but estimates by Jolly's method fluctuated more widely. Temperature accounted for 40% of the variation when predicting population size, the remainder possibly being due to sampling errors. The ratio of females to males varied from about 1.8:1 to 1:1.4. The average duration of adult life varied from 3 to 12 days.