Quick Facts about Japanese Beetles:

• They feed for 6 to 8 weeks from late June through August.
• They eat between the veins of a leaf, leaving it dried and lacey.
• They can stress plant material but rarely inflict enough damage to kill it.

Japanese Beetles do have favorite plants, but they feed on a large variety of trees, shrubs, and flowers - especially on yellow colored rose flowers or ripening fruits like raspberries and grapes.

Favorite plants:

• Linden, birch, cherry and plum trees
• Plants in the rose family
• Grapes and red raspberries
• Virginia creeper
• Porcelain berry vine
• Rose of Sharon and other mallow
• Onethera and many others

Prevention
One way to control Japanese Beetles is to replace favored plants with those they tend to avoid, including boxwood, hydrangea, lilac, euonymus, holly and forsythia. Another prevention strategy is to physically cover plants with a floating row cover. This is a lightweight spun polyester fabric that lets light and moisture through but excludes the beetles from feeding. This is especially helpful for vegetables or raspberries where sprays may be undesirable.

Control
If Japanese Beetles are already present in your landscape you have a few options for controlling the damage they inflict.

1. Physical Removal
   The least invasive method of control is to physically remove the insects from your plants. Japanese Beetles are fairly clumsy and will fall off a branch when it is shaken. Hold a bucket of soapy water under the branch while you shake it to collect the beetles. Use liquid dish soap, as plain water doesn't quite do the trick - the beetles can survive and swim around in it for days.
2. Japanese Beetle Traps
   You can also hang traps that lure beetles using a pheromone scent. These traps have replaceable collection bags or containers to dispose of trapped beetles. You should only use the traps if there is a heavy infestation. Be sure not to place them near the desirable plants - hang them in a nearby area to draw them away.
3. Chemical Control
   Another method of control is with the use of a chemical product. This option may be necessary for large infestations that cause serious plant damage. All general use insecticides will control beetles, and most require direct contact to kill the beetle. Be sure to follow label instructions when spraying.
   
   Spray insecticides later in the day when adult beetles are less likely to fly off and bees may not be working. Apply carbaryl sold as “Sevin” or permethrin or other pyrethroid sprays. You may also apply imidacloprid as a drench in early spring to prevent damage to a favored tree.

For more advice on dealing with Japanese Beetles, call or stop by the Garden Center to speak with one of our horticulturists.

Click here to see our Growing Guide on Japanese Beetles.

Ella Maxwell

Ps. Be sure to watch my talk on Japanese Beetles on the Mid-day Gardener tomorrow! Tune to the WEEK noon news cast and watch for the program around 12:20pm after Mr. Food.