FOR IMMEDIATE RELEASE May 26, 1961 



INSECT SURVEY BULLETIN NO. 6 



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

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

 Survey, University of Illinois College of Agriculture, and cooperating agencies. 

 It is designed to forewarn people in Illinois of impending changes in insect ac- 

 tivity and suggest abbreviated control measures. These reports indicate only gen- 

 eral trends. Each individual should check his own fields to determine local con- 

 ditions. 



Pea aphid populations mushroomed during the past two weeks. In some 

 fields of alfalfa and clover in central and north-central Illinois, damage has been 

 severe. In some areas the population is decreasing rapidly because of a fungus 

 disease of aphids. Aphids killed by this disease are brown and have a flattened 

 appearance. Aphid predators, such as lady beetles (both adult and larvae) and dam- 

 sel bugs, are becoming prevalent and are now further helping to reduce aphid num- 

 bers. To spread rapidly, the fungus disease must have some moisture and warm tem- 

 peratures. Spraying is questionable when brown aphids are numerous and lady beetles 

 are becoming plentiful. In areas where it has been dry and cool, the fungus is not 

 common and a severe aphid problem still exists. 



Examine this year's seedings in small grains, as aphids are migrating to 

 these small plants. It may be necessary to spray these new seedings with malathion. 

 Again the fungus disease and predators may help. 



With hay harvest approaching, apply one pound of malathion or l/k pound 

 of phosdrin. Allow one week between treatment and harvest when applying malathion, 

 and one day with phosdrin. Be sure to clean the weed spray out of the sprayer be- 

 fore using on alfalfa and clover. Phosdrin should be applied only by operators 

 experienced in handling organic phosphates. 



In heavy growths of alfalfa, spray penetration is poor and control is not 

 perfect. If the alfalfa is close to harvest, cut and then spray second growth if 

 the aphids transfer to it. 



Corn borer pupation is approximately 25 percent in the central and north- 

 central sections and 10 to 15 percent in the northern section. Development of corn 

 borer compared with corn growth is similar to 1956, but the overwintering population 

 is not so great this year as in 1956. 



The armyworm situation is not yet serious, but in the southern third of 

 Illinois armyworms have been found in grass and grain fields. No large concentra- 

 tions have been located, but they may be present and overlooked. Examine rank 

 growths of grasses and grains. 



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

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

 7 days for toxaphene on wheat but Ik days on barley. For beef pastures, use toxa- 

 phene j 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. 



