. The hemlock sawfly in Southeast Alaska. Hemlock sawfly; Insect pests Alaska. Figure 6.—Hemlock .sawfly mature cages consumed an average of 82. 38 SE i- 1 3. 74 needles per larva. An F test showed no significant difference at the 5-percent level between single and group-reared larvae in needle consumption per individual. In addi- tion, a chi-square test indicated no significant difference in percent sur- vival between single and group- reared larvae. Therefore, group feeding has no apparent survival value over soli- tary feeding. Incidence of parasitiza- tion or predation of sawfly larvae cou
. The hemlock sawfly in Southeast Alaska. Hemlock sawfly; Insect pests Alaska. Figure 6.—Hemlock .sawfly mature cages consumed an average of 82. 38 SE i- 1 3. 74 needles per larva. An F test showed no significant difference at the 5-percent level between single and group-reared larvae in needle consumption per individual. In addi- tion, a chi-square test indicated no significant difference in percent sur- vival between single and group- reared larvae. Therefore, group feeding has no apparent survival value over soli- tary feeding. Incidence of parasitiza- tion or predation of sawfly larvae could vary under the two types of feeding conditions, however. COCOON SIZE RELATED TO SEX Cocoon measurements indicate that size is a fairly reliable means of sexing sawflies within the cocoons. One hundred and fifty male cocoons had a mean length of SD — larval gonads; A, male; B, female. mm. and a mean width of SD — (fig. 7, A and B). There was no overlap of male and female cocoon lengths within a range of two standard deviations. Therefore, more than 95 percent of the cocoon population could be sexed by measuring the length. This technique provides a useful tool for determining sex ratio of a field population prior to adult emergence. Comparing sex ratios of cocoons and emerging adults could reveal differen- tial mortality of the sexes while in the cocoons. FECUNDITY In order to determine the repro- ductive potential of the sawfly, we allowed 81 females collected in the field as cocoons to oviposit. We then dissected them to determine the num- ber of remaining mature eggs. The mean number of laid and unlaid eggs 7. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Hard, John S; Schmiege, Donald C. [Portland, Or. ] : Institute of Northern Forestry, Pacific Northwest, Forest and Ran
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