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TV*. 7 



FOR IMMEDIATE RELEASE May 22, 196^ 



INSECT SURVEY BULLETIN NO. 6 



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

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

 versity of Illinois College of Agriculture, Illinois Natural History Survey and co- 

 operating 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. 



Armyworms are numerous in luxuriant stands of wheat, barley and rye. Most 

 of the worms are about l/2 to 2/3 grown in southern and southwestern Illinois, but 

 have just hatched this past week in central and western Illinois. These small, newly- 

 hatched worms stay close to the soil surface and are difficult to find since their 

 feeding is slight. Larger worms may be found in grass pastures since moths lay their 

 eggs here first. Do not confuse armyworms with sawfly larvae that are now also being 

 found in grain fields. They are green to yellow, velvety, transparent- skinned larvae; 

 true armyworms are striped and smooth- skinned. The unimportant sawfly larvae can be 

 distinguished from armyworms by the number of abdominal prolegs, the fleshy legs on 

 the underside of the abdomen. Sawflies have six or more pairs of these abdominal 

 prolegs while the true armyworms have only four pairs. 



If there are six or more armyworms per linear foot of drill row, treatment 

 is suggested. Apply insecticides when the worms are 1/2 to 3A inch long; 30$ of 

 their feeding damage will be done from this size until they become full-grown. 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. 



For grass pastures, carbaryl (Sevin), 1 l/2 pounds per acre, or methoxy- 

 chlor, two pounds per acre is suggested. Methoxychlor does not kill the armyworms but 

 does prevent further feeding. Allow seven days between treatment and pasturing of 

 livestock when methoxychlor is used. 



The greatest mistake made in armyworm control is to panic and apply insec- 

 ticides when they are not necessary. Do not use insecticides unless the worms are 

 present in numbers sufficient to warrant treatment. 



High temperatures speed up the rate of armyworm growth, but, at the same 

 time, promote the spread of a disease which kills armyworms. The next two weeks will 

 be the critical time to count live worms and decide on insecticide applications. 



Variegated cutworms may be present in numbers in clover and alfalfa fields. 

 After the first crop is removed and before new growth starts, apply Sevin or toxaphene 

 if worms are devouring the new shoots. Toxaphene should not be applied to hay fields 

 when growth is over four inches. 



Black cutworms are reported to be damaging corn in some fields of central 

 Illinois. If the plant is cut off above the growing point, or heart, the plant usually 

 recovers. If it is cut off below the growing point, the plant will dj^«. jjIf,4P$. fl£ 

 the plants are being cut below the growing point, an application of l/^rotoftcP'cfP »"• 

 dieldrin or three pounds of toxaphene is warranted. Direct the spray at ,th* base of 

 the plant in the soil. Use as much water per acre as possible. Cultivate immediately 

 to cover the insecticide. fjiSilcl^iDl fc* MAttftS 



