FOR BMEDIATE RELEASE June 30, 1961 



INSECT SURVEY BULLETIN NO. 11 



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. 



Face flie s have completed at least one generation this year; eggs are now 

 being laid for another generation and from now on, generations will overlap. This 

 week some herds averaged kO flies per animal. Other herds averaged less than five 

 per animal. Animals in dry lot had the fewest flies. Observe cattle between 

 10:00 a.m. and 3:00 p.m. as flies will be most active during the middle of the day. 



Complaints about face flies on cattle have been received from the area 

 north of a line from St. Louis to Lawrenceville, with the largest populations in 

 the northern half of Illinois. 



The situation is alarming and a control program must be started now and 

 continued faithfully. Do not underestimate the seriousness of this problem. High 

 temperatures speed up the reproductive rate and the increase in face fly numbers 

 will be rapid, reaching an expected peak in mid-August to early September. Take 

 immediate action to control those now present. 



For dairy cattle, apply DDVP commercially prepared face fly bait to the 

 animal's forehead for the next 2 to 3 weeks and then every 3 to 5 days as needed. 

 For beef cattle, use 5 percent toxaphene in a backrubber. Homemade backrubbers 

 work as well as commercial ones. Run a taut line of k to 6 strands of barbed wire 

 from a post about 5 feet above ground to a stake in the ground about 9 feet away, 

 and wrap with gunny sacks. Saturate with the toxaphene solution. Place the back- 

 rubber where it is readily accessible and will be used. Do not treat cattle with 

 toxaphene within 28 days of slaughter. 



The corn borer situation has eased considerably. The last emergence of 

 moths occurred this week and scattered egg laying may continue for another 10 days 

 to 2 weeks. However, there is so much corn attractive for egg-laying that the eggs 

 yet to be laid will be scattered sparsely over a large area, but borer survival 

 from these eggs will be high. Even though first- generation corn borer numbers are 

 not expected to be concentrated In a few fields, the average population over an 

 entire area may be sufficiently high to produce a serious population of second- 

 generation borers in August. 



Examine the most noticeably advanced fields in a community this week as 

 an occasional field may profit from treatment. To determine the need for treatment, 

 examine 50 to 100 plants for signs of borer feeding on the whorl leaves. If 75 per- 

 cent or more of the plants show recent whorl feeding, check the tassel ratio. Meas- 

 ure from the base to the tip of the plant with leaves extended. Split the plants 

 lengthwise, and measure from the base of the plant to the tip of the developing 

 tassel. Divide the tassel height by the plant height, and multiply by 100. This 

 is the tassel ratio. Take an average of 5 representative plants per field. The 

 corn will warrant treatment if the tassel ratio is 30 or above. Applications of 

 insecticides, where necessary, should be applied now. Treatment after borers have 

 drilled into the stalk proper will not be effective. 



