. Bulletin. Insects; Insect pests; Entomology; Insects; Insect pests; Entomology. LIFE HISTORY. 17 average number of young ( per day) over an average period of 19 days, would give birth to 63 aphides. At this rate of reproduction, provided that none of the aphides were destroyed before they had lived an average life, one winged aphis which settles on the hop in the spring would at the end of the fifth generation be the parent of 4,068,989,826 living aphides. These aphides would weigh 2,152 pounds. From these figures the very sudden and extensive infestations by this insect are readily expla
. Bulletin. Insects; Insect pests; Entomology; Insects; Insect pests; Entomology. LIFE HISTORY. 17 average number of young ( per day) over an average period of 19 days, would give birth to 63 aphides. At this rate of reproduction, provided that none of the aphides were destroyed before they had lived an average life, one winged aphis which settles on the hop in the spring would at the end of the fifth generation be the parent of 4,068,989,826 living aphides. These aphides would weigh 2,152 pounds. From these figures the very sudden and extensive infestations by this insect are readily explained. THE FALL MIGRANTS. The nymphs of the fall migrants (fig. 6) became winged in the breed- ing cages at Perkins, Cal., on Au- gust 26 and in the field August 28. Migrants were observed upon plum at Independence, Oreg., September 22, 1912. Young were being deposited there and upon the next visit to the locality, October 16, large numbers of male aphides were observed copulating with the sexual females that had been deposited by the migrants. Many eggs were also present at this time. THE WINTER EGG. The winter egg, when first deposited, is a shiny-green ob- ject, ovate in shape, and a little smaller than the head of a pin (f mm. in length). Soon, how- ever, it turns dark green and then black and appears as a shiny-black point (PI. I, iig. 2) on the branch of the alternate host plant. The eggs are usually deposited close around the buds or on the rough leaf scars, but may sometimes be found upon the smooth parts of the twigs. THE LIFE CYCLE. The entire life cycle where the writer's observations were made is as follows: Two generations occur on the alternate host, the second one being winged. Five and six generations occur on the hop, a part of the fifth becoming winged and depositing young upon the 74956°—Bull. 111—13—3. Fig. 6.—The hop aphis: Nymph, showing wing-pads. Greatly enlarged. (Original.). Please note that these images are extracted from scanned page images t
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