The two insecticides that will do the best job are carbophenothion (Trithion) or 

 azinphosmethyl (Guthion) . They should be applied only by experienced operators. 



CORN INSECTS 



European corn borers . The threat from the first-generation corn borers is about 

 over. Only a few unhatched eggs were found this week, and these were mostly in 

 the northern section. A check of over a hundred of the more advanced fields in 

 the state showed that about 15 percent of the plants were infested. Individual 

 fields ranged from zero to a high of 55 percent for infested plants. In most 

 areas, as much as 50 to 80 percent of the corn acreage is attractive to moths 

 laying eggs and is suitable for good survival of the hatching borer. This has 

 lowered the level of infestation. The percentage of infested plants will still 

 increase slightly in the advanced fields in the north-central and northern sec- 

 tions during the coming week, but there is little likelihood of any widespread, 

 heavy infestations. An occasional field may justify treatment. 



If control is still needed in the central or northern sections for first- 

 generation corn borers, use either diazinon (1 pound per acre) or carbaryl (Sevin) 

 (1-1/2 pounds per acre) as sprays or granules. Allow ten days between treatment 

 and harvest when using diazinon. Commercial applicators may prefer to use para- 

 thion at a half pound per acre. Parathion has a twelve-day waiting period between 

 treatment and harvest. 



The greatest danger from corn borers is now to the late-maturing fields, when 

 the second-generation moths begin to lay eggs. We estimate that about 2 percent 

 of all corn plants are now infested and will produce a second-generation moth. 

 This amounts to a yield of 360 moths per acre of corn. These moths will usually 

 move from the fields in which they emerge into the few fields of late-maturing 

 corn, concentrating their egg- laying there. Many of these late-maturing fields 

 could be heavily damaged. 



Lady beetles . These beetles eat other insects. They are more numerous in corn 

 fields than they have been for years, and they are laying eggs. These predators 

 eat aphids or plant lice, corn-borer egg masses, and newlyhatched corn-borer lar- 

 vae. The beetles have a ravenous appetite- -reportedly eating as much as a tea- 

 spoonful of aphids a day, one at a time. The less spraying the better, for now. 



Corn earworms . On the western side of the state, this pest has been feeding in 

 whorls of corn that is about ready to tassel. Although no control measures are 

 needed at present, these earworms do chew up the whorl leaves and the tassels, 

 making individual plants look bad. 



GENERAL INSECTS 



Grasshoppers . Now is the time to control these pests, while they are still con- 

 cent rated in the areas where they hatched. Also, it is easier to kill them while 

 they are small. 



A spray of 1-1/2 pounds of toxaphene per acre can be applied to fencerows, ditch 

 banks, grass waterways, and roadsides when the grasshoppers are concentrated in 

 any of these places. Toxaphene is preferred if weeds are blossoming and attrac- 

 tive to bees, but do not apply toxaphene to or near fish-bearing waters. Toxaphene 

 can also be applied to corn or soybeans, but not if they are to be used as forage. 



