Studies of Fluctuations in Insect Populations

Publisher Website
Google Scholar
Abstract
Collections were made in north Lincolnshire and east Nottinghamshire, England, where the carrot is the only host-plant, in Feb. and early March each yr. From the number of larvae and puparia collected per hr. the pest was most abundant in 1939. The larvae and puparia were raised to emergence of adults in soil from the place where collected. The only parasite collected was Dacnusa postica. The time of collecting was found to be the normal period when larvae change to puparia. The % of emergence of adults was high in all yrs. except 1940. Failure to emerge may have been due to a blackening disease. The sex ratio of adults at emergence gave a greater proportion of [male]. The peak of emergence of the greatest number occurs abruptly about May 14 and passes quickly. The % of parasitism was low for all yrs. except 1940. A suggestion is made for establishing an insect phenological station to prepare tables of dates of hatching, emergence, etc., of insect pests for different localities and to provide information each year as to the earliness and lateness of the season to aid in control. Treatment of carrot clamps with formalin soln. is recommended.

This publication has 2 references indexed in Scilit: