Cocoon size European and sex pine in the sawfly.

Abstract

Recent very severe epidemics of the European pine sawfly (Neodiprion sertifer Geoff. Hymenoptera, Diprionidae) in Ireland have given cause for concern. During recent investigations which were concerned with damage quantification and host susceptibility, the opportunity was taken to confirm quantitatively the known relationship between cocoon size and sex. Adult females have larger cocoons than adult males. A sample of 300 cocoons was collected in the field, and these; were divided into large and small cocoons. Adult emergence by sex was recorded. 98% were classified correctly. The lengths and diameters of 25 large and 25 small cocoons were measured. The means and standard errors are given below...