200 PESTS OF GARDEN AND FIELD CROPS 
or more generations on some alternate host plant, and survives there 
through the winter. 
When found on garden crops, the lice may be killed by spraying with 
tobacco extract or 5 per cent 
kerosene emulsion. Fumi- 
gation with carbon bisul- 
phide will destroy them, 
using an inverted tub as a 
fumigating chamber. The 
dose should be at the rate 
of one tablespoonful of car- 
bon bisulphide to a 20 
gallon tub. Aphis punk 
may be substituted for the 
carbon bisulphide and a 
light frame of oiled muslin 
may take the place of the 
Fic. 249.— Wingl and winged adults of tub. 
the Melon Aphis on Leaf. Enlarged. Where cotton is infested, 
direct control is impracti- 
cable. In this case adopt rigorous clean culture so that weeds may 
be kept down in and around the field. 
The Pea Aphis (Macrosiphum pisi Kalt.) 
Tn seasons of abnormally dry spring weather a large green plant louse 
becomes abundant on peas. The adult lice are one eighth of an 
inch long, pea-green in color, with prominent dark red eyes, and long legs. 
They feed on the leaves and cluster on the terminal shoots. Usually they 
reach their greatest abundance in midsummer, and disappear in August. 
The lice come to the pea vines from clover fields, where they have 
spent the winter as tiny, black eggs. The first generations live on the 
clover. Winged individuals appear as the season advances, and 
migrate to peas. In August they return to clover. 
Contact sp 
ays may be used in direct control on peas. Tobacco 
extract is effective, or 5 per cent kerosene emulsion may be employed. 
