ILLUSTRATIONS 
PLATES. 
Page. 
Plate I. Fig. 1. — Nymphs and winged forms of the hop aphis (Phorodon hu- 
muli) on hop leaves. Fig. 2. — Winter eggs of the hop aphis 12 
II. Fig. 1. — Wingless progeny of winged hop aphides from alternate 
host. Fig. 2. — Willows along edge of hopyard, which were erro- 
neously supposed to harbor hop aphides 20 
III. Fig. 1. — Normal hop cones and hop cones injured by the hop aphis. 
Fig. 2. — Vines severely injured by the hop aphis, showing lack of 
growth as compared with uninjured vines 20 
IV. Fig. 1. — Hopvines severely injured by the hop aphis, and left in the 
field. Fig. 2. — Enlarged view of damaged and moldy hopvines. . 20 
V. Fig. 1. — Eggs of Hippodamia convergens among hop aphides. Fig. 
2. — Syrphus fly larvae feeding upon the hop aphis 20 
VI. Fig. 1. — Hindu laborer cooking flour paste. Fig. 2. — Boiling and 
mixing plant used at Independence, Oreg 28 
VII. Fig. 1. — Hand pump and barrel on sledge. Fig. 2. — Knapsack spray- 
ing machine in use in hopyard 32 
VIII. Fig. 1. — Power outfit on narrow truck, in use in hopyard. Fig. 2. — 
Filling power outfit from improvised supply wagon 32 
IX. Fig. 1. — Compressed-air spraying machine, showing air bottle, tank, 
reducing valve, and pressure gauge. Fig. 2. — Filling air bottles 
for compressed-air spraying machine 32 
X. Fig. 1. — Hopvine stripped, and tied below the point of stripping, 
showing free condition of all foliage. Fig. 2. — Hopvine stripped, 
and tied above the point of stripping, showing matted condition 
of lower foliage 36 
TEXT FIGURES. 
Fig. 1. Field cages so placed as to catch any hop aphides that might emerge 
from eggs deposited upon the hop roots 11 
2. The hop aphis {Phorodon humuli): Wingless viviparous female 13 
3. The hop aphis: Winged female migrant 14 
4. Head of the hop aphis, showing frontal tubercles 15 
5. Head of the melon aphis (Aphis gossypii) 15 
6. The hop aphis: Nymph, showing wing-pads 17 
7. Diagram showing relative number of aphides in different parts of a 
single hopyard, indicating the increased infestation near Santa Rosa 
Creek 20 
8. Short-pole hopyard, showing dense foliage around base of vines, which 
harbors the hop aphis 36 
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