-2- 



Armyworms have been appearing in no- till corn, particularly corn on sod. Severe dam- 

 age to small plants can occur. Investations are readily controlled by spraying with t 

 carbaryl (Sevin) , malathion, toxaphene, or trichlorfon (Dylox) . Do not feed toxaphene- 

 treated forage to dairy or beef cattle. 



Yellow-striped armyworms are brown to black worms with a yellow stripe along each side 

 of the back. They are present now, but usually are not damaging. 



Common stalk borer infestations continue to be reported from no-till corn on sod. There 

 may be damage all over the field. The worms feed deep in the whorl, giving the plant 

 a ragged appearance as the leaves emerge. This damage may not be too severe; but when 

 these worms tunnel into the stalk proper, plants can be killed or stunted. Control is 

 difficult because stalk borers are protected inside the corn plant. A spray of carbaryl 

 at 1 to 2 pounds per acre directed over the row may be helpful. As the borer leaves one 

 plant and crawls to another, it will contact the insecticide and be killed. 



SOYBEAN INSECTS 



Thistle caterpillars or the larvae of painted lady butterflies have been reported in 

 western and northwestern Illinois, migrating from weeds (especially thistles and re- 

 lated plants) to soybeans and feeding on them. These caterpillars have a black head 

 with a mottled, velvety-black or dark-green body with a pair of light-green stripes 

 down the back and one stripe on each side. The body is covered with dark- tipped 

 spines . 



These caterpillars web the leaves together in a nestlike manner and eat chunks out 

 of the leaf margins, in the same way as grasshoppers. One worm will move a foot or 

 two along the row as it feeds. When full grown (1-1/2 inches), the larvae become sil- i 

 very, pink, hard-shelled cocoons attached to the undersides of the leaves. 



In general, infestations are usually much less serious than they appear to be. Soy- 

 beans can withstand considerable defoliation (30 to 40 percent) before bloom without 

 greatly affecting yields . Toxaphene and carbaryl (Sevin) have both provided good con- 

 trol of this insect. Do not feed soybeans as forage to livestock if treated with toxa- 

 phene . 



LIVESTOCK INSECTS 



Face fly populations on cattle have about doubled during the past two weeks. For de- 

 tailed control recommendations, see Bulletin No. 11, June 1, 1973. 



House mosquito larvae are developing in the effluent of livestock waste lagoons. Even 

 a small lagoon (as small as a twentieth of an acre- -2, 000 square feet) can produce mil- 

 lions of adult mosquitoes in a single summer. Livestock and humans in the immediate vi- 

 cinity of the lagoon suffer most. Large lagoons (a quarter of an acre or larger) with 

 low embankments will generally provide less-desirable conditions for mosquito develop- 

 ment (greater wave action from the wind) than small lagoons with high, steep banks. 



Follow these suggestions to reduce and help eliminate mosquito breeding in your waste 

 lagoon : 



1. Remove the marginal vegetation including any flooded vegetation for about three 

 feet from the edge of the effluent all around the lagoon. Rake the dead vegetation 

 and any floating debris away from the edge of the effluent. 



2. The marginal vegetation can be killed easily with a contact herbicide. Dr. Marshal 

 McGlamery, University of Illinois Agronomy Department, suggests a herbicide mixture 



( 



