-2- 



field. This is the tassel ratio. The corn will warrant treatment if the tassel 

 ratio is 30 or above, but if possible do not treat until the ratio is at least 

 35 and preferably k$. However, treatment after borers have drilled into the stalk 

 proper will not be effective. 



DDT is still the most common insecticide for corn borer. Apply 1 l/2 lb. 

 per acre as a spray or 3/^ to 1 lb. per acre as granules. 



Other insecticides approved for use against corn borer are endrin and 

 toxaphene. Do not feed ensilage or stover of corn treated with DDT or toxaphene to dairy 

 cattle. Corn treated with DDT granules may be used as ensilage or stover for fat- 

 tening cattle provided they are removed from the treated forage 90 days prior to 

 slaughter. Endrin may be used provided label restrictions are followed. 



Armyworms ; A few newly hatched to almost full-grown worms were found on 

 luxuriant grasses in northern Illinois this week. They may also be present in grassy 

 spots in corn fields. Normally high temperature promotes a disease of armyworms and 

 keeps their numbers at non-economic levels in Illinois during the summer months. 



Face flies ; Populations are increasing steadily now. Observe cattle in 

 the pasture, not in the buildings, to find out how abundant these flies are. Make 

 counts on clear days between 10:00 a.m. and 3:00 p.m. 



To control these flies on dairy cattle, brush DDVP sirup baits on their 

 foreheads. 



Beef producers with cattle on pasture should keep backrubbers well satu- 

 rated with % toxaphene in oil. Allow 30 days to elapse between application of 

 toxaphene to beef cattle and slaughter. Toxaphene cannot be used on dairy cattle. 



Stable flies and horn flies are becoming more abundant. For dairy cattle, 

 apply 1 to 2 oz. daily of an oil-base spray containing DDVP or pyrethrin sprays with 

 tabatrex or R-326. For beef cattle, spray every 3 or k weeks with 0.5$ toxaphene 

 water-base spray at the rate of 1 to 2 qt. per animal. Allow 28 days between treat- 

 ment and slaughter when using toxaphene. 



Caution : Before applying insecticides, read the labels carefully and 

 follow all precautions. This not only will insure personal safety, but will also 

 eliminate insecticide residue hazards. 



********** 



This weekly report was prepared by H. B. Petty, Illinois Agricultural 

 Extension Service and Illinois Natural History Survey, in cooperation with the USDA 

 Agricultural Research Service, Plant Pest Control Branch, from information gathered 

 by entomologists and cooperators who send in weekly reports from their own local- 

 ities. 



HBP:dl 

 6/29/62 



