Masked chafer adults are becoming very uncommon. Because these annual white grub adults do not feed, they die after about two weeks of mating and egg laying. We are also seeing fewer Japanese beetle adults, although they will be found easily until about the middle of August. As stated in previous issues, conditions are right for large numbers of white grubs to cause heavy damage to irrigated turf starting in mid-August. Golf-course workers should realize that Japanese beetle grubs attack bentgrass as well as Kentucky bluegrass, perennial ryegrass, and tall fescue. Thus, damage is very possible on bentgrass greens and fairways. Application of imidicloprid (Merit) or halofenozide (Mach 2) is warranted in irrigated turf at this time to prevent severe damage later.
Black turfgrass Ataenius is pupating in northern Illinois. This white grub feeds on bentgrass as well as many other turfgrasses, and it is found only on highly maintained turf such as golf courses and some lawns. Only 1/4 inch long when fully grown, these black beetles will be showing up in the baskets of greens mowers in the next few days. This insect has two generations per year. The second generation coincides with Japanese beetle grubs and annual white grubs, so an application for those insects also controls this generation of Ataenius.