. Biennial report of the Oregon State Board of Horticulture ... Horticulture -- Oregon; Fruit-culture -- Oregon; Gardening -- Oregon. APPENDIX. 401 THE HOP PLANT-LOUSE. (Phorodon humuU.) By Pkok. ('. V. LIFE-HISTORY. Wherever it occurs, whether in England or on the continent of Europe, in New York, Wisconsin, or on the Pacilie Coast, the hop plant-louse has substantially the same life-round. The eggs are laid in the fall on dif- ferent varieties and species of the plum, both wild and cultivated. They are small, glossy, black, ovoid, and are attached to the terminal twigs, especially i
. Biennial report of the Oregon State Board of Horticulture ... Horticulture -- Oregon; Fruit-culture -- Oregon; Gardening -- Oregon. APPENDIX. 401 THE HOP PLANT-LOUSE. (Phorodon humuU.) By Pkok. ('. V. LIFE-HISTORY. Wherever it occurs, whether in England or on the continent of Europe, in New York, Wisconsin, or on the Pacilie Coast, the hop plant-louse has substantially the same life-round. The eggs are laid in the fall on dif- ferent varieties and species of the plum, both wild and cultivated. They are small, glossy, black, ovoid, and are attached to the terminal twigs, especially in the more or less protected crevices around the buds (Fig. 1). From this egg there hatches in the spring, about the time when the plum buds begin to Fig. 1—Winter eggs of the Hop Plant-louse, burst, a Stout female plant-louse, and shriveled skin of the sexual feniaie . • , which laid them—enlarged. known as the Stem-mother, which differs from the summer individuals by having shorter legs and shorter honey- tubes (Fig. 2). She gives birth, without the intervention of the male, to living young, and this method of propagation continues till the last generation of the season. The second generation grows to full size and gives birth to a third, which becomes winged (Fig. .3), and develops after the hops have made con- siderable growth in the yards. The winged lice then fly from the plums to the hops, de- serting the plum trees entirely and settling upon the leaves of the hops, where they begin giving birth to another generation of wing- less individuals. These multiply with astonishing rapidity* for from five to twelve generations, carrying us in point of time to the hop-picking season. There then develops a generation of winged. 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 Oregon. Board of Horticulture
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