. The hemlock sawfly in Southeast Alaska. Hemlock sawfly; Insect pests Alaska. 240 feeding instars and females five. A graph of frequency of larval head cap- sule sizes (fig. 3) shows five distinct peaks. When these five peaks were plotted over date of occurrence, how- ever, the fourth and fifth peaks oc- curred simultaneously (fig. 4). This indicates four feeding instars for each sex, the fourth peak representing fourth-in star males and the fifth peak indicating fourth-instar females. Two additional late larval collections were made, and head capsule size frequen- cies plotted by sex (fig. 5
. The hemlock sawfly in Southeast Alaska. Hemlock sawfly; Insect pests Alaska. 240 feeding instars and females five. A graph of frequency of larval head cap- sule sizes (fig. 3) shows five distinct peaks. When these five peaks were plotted over date of occurrence, how- ever, the fourth and fifth peaks oc- curred simultaneously (fig. 4). This indicates four feeding instars for each sex, the fourth peak representing fourth-in star males and the fifth peak indicating fourth-instar females. Two additional late larval collections were made, and head capsule size frequen- cies plotted by sex (fig. 5, A and B). The male peaks, which include a few prepupal larvae, coincide in size range with the fourth peak of figure 3. The female peaks overlap the fourth. o to O tO o AO to > to o to HEAD CAPSULE SIZE CLASSES (mm.] Figure 3.—Hemlock sawllv larval head capsule sizes (1,083 larvae), Limestone Inlet, 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 Range Experiment Station, U. S. Dept. of Agriculture
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