-2^~7 



FOR IMMEDIATE RELEASE May 28, I96U 



INSECT SURVEY BULLETIN NO. 7 



This is the seventh in a series of weekly bulletins on the general insect 

 situation in Illinois (fruit insects excepted), prepared by entomologists of the 

 University of Illinois College of Agriculture, Illinois Natural History Survey and 

 cooperating agencies. It is designed to forewarn people in Illinois of impending 

 changes in insect activity and to suggest abbreviated control measures. These re- 

 ports indicate only general trends. Each individual should check his own fields 

 to determine local conditions. 



Armyworm populations appear to be largest south of Route 9 and in the 

 west- southwestern, western and central areas of the state. Numbers of worms vary 

 greatly from field to field, making it necessary to examine each field. Grass pas- 

 tures and grass waterways as well as thick and luxuriant stands of small grains are 

 infested. Armyworms now are beginning to migrate in search of more food after they 

 have stripped the leaves from the wheat or grass. 



Fly parasites are beginning to deposit eggs on the worms, but it may be 

 too late to control this generation. We have had one report of a disease killing 

 about 10 percent of the migrating worms. 



To repeat last week's comments--you do not need to apply insecticides 

 until armyworms are at least l/2 inch and usually 3 A inch long; most feeding 

 damage is done after they reach this size. Do not become excited and treat when 

 it is not necessary. Carefully examine the plants, the debris on the soil and the 

 soil crevices; you should find six or more worms per linear foot of drill row to 

 justify the expense of treating. If there are fewer than six per linear foot, 

 treatment may be warranted only if the worms are cutting off the heads of wheat. 



If insecticides are needed, apply dieldrin, l/8 to l/k pound per acre, 

 or toxaphene, 1 l/2 pounds per acre. Allow one week to elapse between treatment 

 and harvest of the grain for wheat and rye, but allow lk days when toxaphene is 

 used on barley. Do not use the straw for livestock feed. 



For grass pastures, hay crops or places where there is danger of excessive 

 drift from small grain fields onto dairy pastures, use carbaryl (Sevin), 1 l/2 

 pounds per acre, or methoxychlor , two pounds per acre. Methoxychlor does not kill 

 the armyworms but does prevent further feeding. Allow seven days between treatment 

 and harvest or pasturing by livestock when methoxychlor is used. 



Do not contaminate fish-bearing waters with toxaphene or dieldrin. 



Black cutworms are damaging corn in several areas, but mostly in the 

 northern half of the state. If the plant is cut off above the growing point, or 

 heart, it will usually recover. If it is cut off below the growing point, it will 

 die. If 10 percent or more of the plants are being cut below the growing point, 

 an application of l/2 pound of dieldrin or three pounds of toxaphene is warranted. 

 Direct the spray at the base of the plant in the soil. Use as much water per acre 

 as possible. Cultivate immediately to cover the insecticide. If the field has been 

 destroyed and insecticides are not to be used, consider either replanting with soy- 

 beans or, if replanting with corn, delay a few days to allow the worms to mature, 

 and use a hybrid that will mature before frost. 



Wireworms are also abundant in spots in some fields. If replanting is 

 necessary, either leave the old stand and straddle the rows to replant or if disk- 

 ing up the old stand, broadcast aldrin or heptachlor at 1 l/2 pounds per acre be- 

 fore disking or use 1 pound per acre as a row application at planting. 



