We are in the middle of the bloom of Spiraea x vanhouttei in central Illinois, with more advanced stages of bloom to the south and earlier bloom periods in northern Illinois. Refer to last week’s newsletter for a list of susceptible insects that relate by phenology to this bloom. The cooler temperatures of the week of May 13 coupled with those predicted for the week of May 20 will slow down insect development, allowing more time to apply control measures. Most insects do not develop at temperatures below 50°F.
Periodical cicada emergence has been reported in southern Illinois. Emergence has been reported by Growmark in southern Monroe County west of Red Bud, as well as by Master Gardeners in St. Clair County. Both of these locations are outside of the range of this brood of cicadas as reported in the last issue of this newsletter. The source of information for last week’s article was a 1975 publication by Lewis J. Stannard, Jr. Information published by Chris Simon in 1988 shows this brood also present in Monroe, Randolph, and St. Clair counties in southwestern Illinois. In southeastern Illinois, this brood has also been found in the Wayne County area to the west and in the Champaign, DeWitt, and Douglas County area northwest of the areas reported last week. Periodical cicadas probably move too slowly to have spread that far in the one brood that would have occurred between these publications. Simon undoubtedly had access to more complete information than Stannard.
Unusually high numbers of the large ground beetle Calosoma are being found in the Champaign-Urbana area. This 1.2-inch long beetle is broadly oval with long black legs and antennae. There are species with purple wingcovers and others with bright metallic green wingcovers that occur in Illinois. The ones being seen currently have green wingcovers. These beetles are commonly known as fiery searchers or caterpillar hunters. One species, C. sycophanta, was introduced from Europe into the northeastern United States in the early 1900s to control gypsy moth caterpillars. Both the larval and adult stages feed on caterpillars, with the adults climbing through trees in search of caterpillars. Once introduced, this ground beetle spread much faster than the gypsy moth and has been known to occur in Illinois for decades. These adult beetles are attracted to lights at night; they may be noticeable due to their large size and bright colors in the evening or in parking lots and other brightly lit areas in the morning. They are beneficial insects and should not require control measures. They are large and predaceous beetles, and they will probably bite if they are handled.