This has been a banner year for japanese beetles.

Controlling adult Japanese beetles is difficult when populations are high. They feed on at least 275 different plant species and will fly in from neighboring areas if you have plants that are especially attractive such as plants in the rose family. The least toxic control is going out in the morning or early evening and knocking or sweeping the adults from trees, shrubs, and garden plants into a bucket of soapy water. Insecticides provide only temporary relief when populations are heavy. Some organic sprays contain the active ingredients neem, pyrethrins (harmful to bees), or spinosad (harmful to bees when wet but has little effect when sprays dry). Acetamiprid is a synthetic insecticide that provides systemic control of Japanese beetle adults on Ornamental plants with minimal effects on pollinators. Look for a product that has this single ingredient and is not mixed with other active ingredients. Follow all label directions and avoid treating plants when pollinators are present. For more information on Japanese beetle-http://extension.umd.edu/hgic/japanese-beetles

We have not recommended milky spore for grub control for many years. University research has indicated it performs poorly. The other downside is that it only controls Japanese beetle grubs and there are many other types of grubs in Maryland lawns.

Reasons to apply a grub control may be: past history of grubs and damage; if you have a sprinkler system that keeps the soil moist for egg laying; and if we have weather conditions i.e., wet summer and lush lawns while the adult beetles are active in June. It is too early to see any type of grub damage now. The turf can be rolled back from the soil like a carpet usually in late summer to early fall. Look for grubs in the upper soil surface. You may need to dig with a trowel. It is normal to find some grubs in the area. If the grub count exceeds 6-10 per square foot, you may want to consider treating for grubs. Grub controls are applied as a preventative (time frame is mid June through August). You will have to decide if you want to treat. Look for a season long grub control that contains the active ingredient Chlorantraniliprole. This product is more environmentally friendly. mh

Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension horticultural consultants. Please subscribe to our free, monthly e-newsletter!