Population and Mortality Assessment During the Egg and Larval Stages of the Larch Sawfly, Pristiphora erichsonii (Htg.)

Abstract

This contribution is the eighth in a series of papers on sampling techniques used in population studies of the larch sawfly (Ives, 1955; Ives and Prentice, 1958; Buckner, 1959; Ives, 1959; Ives and Prentice, 1959; Ives and Turnock, 1959; and Turnock, 1960). Although the greatest proportionate mortality usually occurs in the cocoon stage of this insect, the largest amount of mortality in terms of absolute numbers occurs between oviposition and the completion of larval feeding. This paper presents a method for estimating seasonal increments to the egg and larval populations and alternative methods for estimating mortality during these stages. Examples are also provided of the integration of these methods with previously developed techniques for estimating egg populations and foliage weight.