- 1 ^^ August 11, 1961 



INSECT SURVEY BULLETIN NO. 17 



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 

 to suggest abbreviated control measures. These reports indicate only general trends. 

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



Corn borer moth flight is well under way, and egg laying has begun. About 

 75 percent of the first-generation borers are going to pupate, and moth emergence 

 will continue for the next several weeks. Damage to field corn by second genera- 

 tion will probably be about the same as it has been for the past four years. 



Sweet corn for canning and fresh market may be more heavily infested this 

 year than for the past four years, however. In addition, corn earworm moths con- 

 tinue to lay eggs. This earworm problem is expected to become more severe. Corn 

 to be harvested after August 20 should be protected from damage by a regular in- 

 secticide program. In addition, good earworm and corn borer control means fewer 

 sap beetles and picnic beetles in the field. 



Grasshoppers have begun to migrate from roadsides, ditch banks and hay 

 crop fields to soybean and corn fields. Damage is now evident, particularly on the 

 margins of the fields. Some alfalfa and clover fields have been stripped of leaves, 

 and the hoppers are leaving these fields rapidly. 



This situation is very severe in localized areas, but nearby areas may 

 have only normal populations. These extremes may be correlated with the egg laying 

 of 'hoppers last fall and with severe rainstorms this spring which killed the un- 

 protected 'hoppers shortly after they hatched. These same timely rains may have 

 missed the severely infested areas. The grasshopper infestation is more severe in 

 the northern areas of Illinois. 



To control 'hoppers in soybeans and corn, apply l/h pound of dieldrin or 

 1 1/2 pounds of toxaphene per acre. Allow kO days to elapse between application 

 of dieldrin and grain harvest. Do not feed toxaphene -treated forage to dairy 

 animals or animals being finished for slaughter. 



Use one pound of malathion per acre on hay crops or pasture for dairy 

 cattle or animals being finished for slaughter. Allow one week to elapse between 

 application and harvest or pasture. 



Fall armyworm feeding is appearing in late-planted fields of corn. The 

 leaves have great areas gouged out of them, giving the plants a ragged appearance. 

 The worms are commonly found in the whorl, and there will usually be several in- 

 fested plants in one spot in the field. Populations of this insect will probably 

 increase from now until late September. Control is difficult after the damage be- 

 comes evident, but granular insecticides may penetrate the whorl more readily than 

 sprays. Use 1 1/2 pounds of toxaphene or DDT. Do not treat corn to be used for 

 ensilage or stover for dairy cattle or animals being finished for slaughter. 



Face flies continue to present a problem throughout the northern two- 

 thirds of Illinois. However, the problem is most severe in the northern and north- 

 central parts of the state. Populations of these flies can be expected to increase 

 for the next month. DDVP face fly baits have controlled these flies when used 



