Issue 8, June 11, 2012
Japanese beetle is emerging in central Illinois. Only an occasional beetle has been reported, which are probably males. Females should emerge in noticeable numbers during the week of June 11 and both sexes will make their presence known feeding on trees and shrubs. Refer to last week's newsletter for more information.
Fall webworm should be present in the southern half of the state. From Lincoln, IL south, this insect has a late spring generation in addition to the late summer generation found throughout the state. This insect lives in groups that spin silk tents over the ends of tree branches, enclosing the leaves that they feed upon. When those leaves are eaten, the silk tent is enlarged. Crabapples, maples, hickories, walnut, and other forest trees are attacked. Generally, the health impact is not serious enough to warrant control, but treatment for aesthetic reasons may be warranted. Bacillus thuringiensis kurstaki (Dipel, Thuricide, others), spinosad (Conserve), and various labeled pyrethroids are effective in providing control. As the silk tent is water-proof and spray-resistant, use high pressure to break up the webbing and get the spray inside to the caterpillars.
Fall webworm damage on crabapple.
Cicada killers, sand wasps, and other ground-nesting wasps are becoming noticeable. Cicada killers usually nest in flower beds and other areas of sparse turf but will dig burrows in high quality turf. Sand wasps as well as cicada killers nest in sandy areas such as golf course bunkers, volleyball courts, and sand boxes. Although they rarely sting, concern from clientele and the public may warrant control. A dust formulation insecticide such as carbaryl (Sevin) or a labeled pyrethroid applied lightly to dry soil around the hole will usually kill the female wasp tending the burrow. Sand boxes can be covered during the day except when in use to discourage the wasps. They fly during the day and need frequent access. Without it, they will go elsewhere. Once the females are killed or leave, the cruising male wasps will leave.
Cicada killer adult on post.