200 



PESTS OF GARDEN AND FIELD CROPS 



or more generations on some alternate host plant, and sm'\'ives there 

 through the winter. 



When found on garden crops, the Uce 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 mushn 

 may take the place of the 

 tub. 



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.) 

 In 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 Uve on the 

 clover. Winged individuals appear as the season advances, and 

 migrate to peas. In August they return to clover. 



Contact sprays may be used in direct control on peas. Tobacco 

 extract is effective, or 5 per cent kerosene emulsion may be employed. 



Fig. 249. — Wingless and winged adults of 

 the Melon Aphis on Leaf. Enlarged. 

 Original. 



