No. 7/June 12, 2017

Rose Chafer
Rose chafer adults have emerged in Illinois, although damaging numbers are unlikely except in areas with sandy soils such as the Kankakee, Will, and Mason County areas. Adults live for about one month. They contain a heart toxin that can kill birds and mammals that eat them.

It is time to treat for bagworms in southern Illinois. Bagworms are just hatching in central Illinois, and they will hatch in northern Illinois by late June. Upon hatching, young caterpillars crawl out of their mother's bag where the eggs were laid and crawl upward. They get to the top of the tree and spin out silk, creating a long streamer that catches in the wind, carrying the young bagworm to new hosts.

Modified Growing Degree Days (Base 50°F, March 1 through June 8)
Insect development is temperature dependent. We can use degree days to help predict insect emergence and activity. Home, Yard, and Garden readers can use the links below with the degree day accumulations above to determine what insect pests could be active in their area.

Gymnosporangium Rusts
I covered Gymnosporangium rusts on Eastern Red Cedar in Issue 2 of this newsletter. That article focused on infections of evergreen hosts. We are now seeing symptoms on many rosaceous plants, which serve as alternate hosts. Apples, crabapples, hawthorns and quince are some of the more commonly affected plants. Symptoms vary depending on the host plant and the rust species involved.

It was nowhere and suddenly it is everywhere. Perhaps you've noticed it too. I was unfamiliar with this weed until about two years ago when a groundskeeper inquired about it saying that it was all over campus in the landscape beds. Sure enough it was. We were both stumped as to what it was and thus turned to the INHS botanists for assistance. Only one of my typical go to weed ID reference books include this weed, Weeds of the Nebraska and the Great Plains, yet this plant can be found across the country.