By Barbara Whipple, Dundee Nursery and Landscaping
Japanese Beetle image courtesy USDA
I dread the first-of-the-season baggie or jar full of Japanese beetles that somebody brings to the Information Desk for me to identify. With Japanese beetles, once they start, they go on for six to eight weeks. And it’s that time, again…so-o-o, here’s what to do:
1. You’ve got a few beetles on a few plants. In this situation, just shake them off the plants into a bowl or pail of soapy water, or pick them off if needed. The presence of a few beetles draws more so check your plants regularly.
2. You have infested plants, a tree or vine or rose garden covered with beetles. First, take your hose and spray as many beetles as you can off the plants. Then come to Dundee for an insecticide such as “Eight,” a permethrin that kills insects on contact.
“Eight” is available as a ready-to-use, as a concentrate for use with your own sprayer, or as a concentrate with a hose-end spray attachment. Check the plants regularly for new infestations because Japanese beetles fly in from anywhere up to 1,000 feet away.
3. Every plant in your yard is infested with Japanese beetles. See 2. above. You might also be interested in a lists of plants the University of Minnesota says Japanese beetles are attracted to:
American linden
Mountain ash
Apple and crabapple
Birch
Norway maple
Cherry and plum trees
Roses
Hollyhocks
Grapes
Raspberries
Englemann and Boston ivy
If your yard is full of these plants, you might want to consider making a few changes to the following plants that the University says seldom attract Japanese beetles:
Oak
Red and Silver maple
Boxelder
Green ash
Poplar
Arborvitae
Fir
Hemlock
Juniper
Pine
Spruce
Yew
American elder
Common lilac
Euonymus
Rhododendron
While you aren’t going to cut down a beautiful, mature tree because it attracts beetles, you also don’t want a yard full of nothing but beetle attractors. Roses need not be grouped together, making them easier for beetles to find, but may be mixed among other plants less attractive to the beetle. Japanese beetles don’t like any evergreens, so think of ways to incorporate a variety of them in your landscape. The insects may be more plentiful, but we are smarter. We can use our knowledge to lessen the irritation insects present.