INSECTS INJURIOUS TO CORN 169 



whatever injury may occur. Rarely is corn on land not in corn 

 the previous year seriously injured, and where infestation has 

 not been serious throughout a community, it may usually be 

 grown two years in succession with safety. 



The proper fertilization of plants affected with root insects 

 is always of great importance, enabling the plant to make a crop 

 in spite of them if the attack is not too severe. Professor F. M. 

 Webster observes that land which has been fertilized with barn- 

 yard manure is much less injured by this insect than that whore 

 commercial fertilizers are used. 



As the ants not only spread the pest during spring and summer, 

 but house the eggs in their nests over winter, any means for 

 destroying their nests will be of importance in controlling the 

 aphides. Where it is practicable, deep plowing in late fall and 

 winter, with thorough harrowing, will break up the nests, and 

 land so treated has shown decidedly less injury the next season. 

 Similarly plowing deeply and harrowing several times in spring 

 not only breaks up the ants' nests, but destroys the weeds and 

 grasses upon which the aphides feed before corn is up, and also 

 furnishes the best possible seed-bed and soil conditions. This 

 should be particularly thorough in low spots where weeds are 

 thickest and where the aphides appear first. Such spring cultiva- 

 tion has been demonstrated as very effective in the control of 

 the pest. In recent years Professor S. A. Forbes has conducted 

 experiments in Illinois which seem to show that dipping the seed 

 in a repellant such as a lemon oil will render it obnoxious to the 

 ants, and thus protect the hill. This has not proven successful, 

 however, when heavy rains followed planting and washed off 

 the repellant. Lemon oil was used by adding 1 gallon of wood 

 alcohol to 1 pint of oil of lemon, of which 3 fluid ounces (6 table- 

 spoonfuls) were stirred into each gallon of seed used, being sure 

 that all the seeds were well coated. Such a treatment cost about 

 ten cents per acre and resulted in reducing the number of 

 aphides 89 per cent and the number of ants 79 per cent, so that 

 it may well be given a trial, but the chief reliance should be placed 

 upon rotation and early cultivation. 



