Japanese beetles should be making their appearance in your garden soon. Our long, cold winter didn’t really touch these beetles which spent the winter snuggled up in the ground as grubs. The adult beetles can be very destructive and not very selective in what they eat. There is no easy guaranteed solution for dealing with these pests. The beetles start as a white grub and the adult beetles typically come out in late June and hang around through August. During that time they eat, mate, and lay eggs in your lawn.
When in feeding stage the grubs eat the roots of lawn grass and can reduce the root system enough that grass can die in the summer heat and dry winds. The adult beetles chew on leaves, leaving them with a lacy or skeletonized look. Their favorite plants include grape vines, crabapples, hollyhock, roses, plum, apples, lindens, and birch to name a few.
What can you do? There are a variety of sprays, lawn treatments and traps. Grabs can be treated with a granular treatment, Bonide Grub Beater, which can eliminate grubs and the lawn damage they cause. As for the adult beetles you can physically remove them from plants and toss them in soapy water.
If you are looking for a chemical approach, a spray like Bonide’s Captain Jacks Dead Bug, Beetle Killer, or Eight can be used. These sprays can also damage beneficial insects like bees so be sure to read and follow all directions on the label and don’t spray where bees are feeding.
Traps can also be used to attract beetles. Many go into the traps, but some may still find their way onto desirable plants so be sure to hang traps away from the plants you are trying to protect.