INSECT PESTS AND THEIR CONTROL 969 



Treatment. — Use sprays of nicotine or tobacco extract, kerosene 

 emulsion (5 to 10 per cent strength) or fish-oil soap just after the aphids 

 appear and at such other times as may be necessary. Spray thoroughly, 

 being sure to wet all plant lice. If spray does not adhere to the bodies of 

 insects, add 2 or 3 pounds of laundry soap to 50 gallons of spray solution, 

 or preferably an equal amount of resin fish-oil soap as a sticker. For under- 

 ground forms practice rotation of crops or use soil fumigants. 



White Grubs (Lachnosterna spp.). — White grubs or grub worms are 

 the larvse of the common brown beetles known as May beetles or June 

 bugs, commonly seen around lights and on the screens in the spring and 

 summer. Their natural breeding place is grass lands, but they are found 

 in fields and gardens feeding upon the roots of many plants. 



Treatment. — No successful treatment is known. Practice crop rotation 

 when necessary. Fall plowing will be of some benefit. Do not plant 

 crops liable to be injured, as strawberries, on recently broken sod land. 



Wire Worms (Elateridce). — Slender, brown, hard, shining larvae, ^ 

 inch to 13^ inches long, body divided into several segments which show 

 plainly three pairs of small legs near front end of body. Their natural 

 breeding place is grass lands, but they feed on or in the roots of many 

 garden and field crops. Two years or more are required for development. 



Treatment. — -No satisfactory treatment has been found. Rotation of 

 crops, preventing ground from remaining long in grass, and late fall plow- 

 ing followed by repeated harrowing for a month or two are the best means 

 of preventing their increase. Seeds might be protected by the use of some 

 substance as a repellent which would not injure germination. 



GENERAL CROP INSECTS 



The Army Worm {Leucania unipuncta, Haworth). — In general appear- 

 ance it resembles cutworms. About \]/> inches long, dark in color, with 

 three yellowish stripes down the back. The adult insect is a dull brown 

 moth, often seen about lights in the spring. The worm feeds naturally on 

 wild grasses, but when it is abundant marches across fields, destroying 

 many crops, including corn, wheat, oats and related crops, as well as many 

 truck crops. 



Treatment. — The march of the worms to uninfested fields may be 

 checked by a deep dust furrow through which a log is dragged occasionally 

 to crush the worms and to maintain a thick coat of dust on the sides. 

 Scattering poison bran mash through infested fields will often prove very 

 effective. Late fall plowing and cultivating will help in destroying over- 

 wintering worms. 



The Alfalfa Leaf Weevil (Phytonomus posticus, Fab.). — This insect, 

 which has been accidentally introduced into the United States from Europe, 

 now threatens the alfalfa industry of the country. From a small field 

 near Salt Lake, where it was first found, it has spread through the surround- 

 ing country until it has gone as far as Wyoming and Idaho. In the spring 



