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FOR IMMEDIATE RELEASE May 19, 19^1 



INSECT SURVEY BULLETIN NO. 5 



This weekly bulletin on the general insect situation in Illinois (fruit 

 insects excepted) is prepared by entomologists of the Illinois Natural History Sur- 

 vey, University of Illinois College of Agriculture, and cooperating agencies. It 

 is designed to forewarn people in Illinois of impending changes in insect activity 

 and suggest abbreviated control measures. These reports indicate only general 

 trends. Each individual should check his own fields to determine local conditions. 



Armyworms were found in barley fields in the south third of Illinois this 

 week. It was still too early to diagnose the situation, as the worms were so small, 

 some just newly hatched, that accurate counts could not be made. Also, moth flight 

 was greater this week than at similar times during the past 3 years. This may mean 

 that eggs are still being deposited. Furthermore, armyworms thrive best in cool, 

 damp weather. 



On the basis of previous experience, timothy and other grassy fields will 

 probably be the first areas where armyworms will be noticed. Next will be barley 

 and rye fields, and then wheat. 



During the next few weeks, observe fields of luxuriant grass and small 

 grain crops. Down spots in grains are the first place to examine. If worms are 

 numerous, examine other areas in the field. If there are six or more per linear 

 feet of drill row, treatment will be profitable. However, it will not be needed 

 until the worms are about 1/2 inch long, as they do little damage until about half 

 grown. 



Toxaphene, 1 l/2 pounds, or dieldrin, l/h pound per acre, is recommended 

 for small grains. Allow 7 days between treatment with dieldrin and harvest, and 7 

 days for toxaphene; barley, however, requires 1^ days. For beef pastures, use 

 toxaphene; allow k2 days between last grazing on treated pastures and slaughter. 

 For dairy pastures, use 2 pounds of methoxychlor, or 1 pound of malathion per acre, 

 but do not graze for one week after treatment. 



Black cutworms : Although we have no information on moth abundance, con- 

 ditions are ideal. The moths lay the eggs in wet spots in fields and in bottom 

 land or overflow areas. They have plenty of areas to choose from this year. 



Aldrin or heptachlor, 1 1/2 pounds per acre, broadcast and disked in 

 before planting, will protect against cutworm attack. Row treatments have given 

 erratic results. When no preventive measures have been used and worms are cutting 

 corn below the heart of the plant, apply 1/2 pound of dieldrin, 3 pounds of toxa- 

 phene or l/k pound of endrin per acre, and direct the spray at the base of the 

 plant. 



Sawf ly larv ae feed on wheat leaves. Ordinarily they are of no economic 

 importance, and control measures are rarely recommended. They are easily confused 

 with true armyworms, however. A sawfly has at least six pairs of abdominal prolegs 

 compared with four pairs for the armyworm. 



Corn borer : Half of the overwintering corn borers have pupated in 

 southern Illinois, but pupation has just started in central Illinois. This is 

 about one week later than normal. The area north of a line from St. Louis to 



MAY Z2 1361 

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