Japanese Beetles in the Roses

Adult Japanese beetles are one quarter to one half inch long with copper colored wing covers and a shiny metallic green head. Between the green head and tiny tufts of white hair along their side you’ll recognize them easily as they happily munch on your roses.

While they generally don’t eat dogwood, forsythia, holly, lilac, evergreens and Hosta, they’ll eat darn near everything else. These beetles feed on flowers and fruits making a skeleton of the leaves by eating the green parts and leaving the veins. Adults are most active from 9 a.m. – 3 p.m. on warm summer days. These voracious pests prefer plants in direct sun, so shady areas are usually less damaged.

The bacterial spore, sold as ‘Doom’ or ‘Grub Attack’ is generally used to control these pests. Using a hormone lure in your yard simply attracts more beetles to your yard. Put the lure somewhere else a hundred yards away encouraging the beetles to go elsewhere. Unfortunately, reducing the beetles in your yard will not reduce their attacks in succeeding years. These beetles are great fliers and can travel upwards of ten miles from where they hatched.

Handpicking is also effective on your prized plants – drop the beetles into a bucket of soapy water to kill them. There is some data that suggests hand picking is as effective as spraying noxious chemicals and you know you have killed the beetle when it drowns in your soapy bucket. One trick is to hold the bucket of soapy water under the plant and then shake the plant. Beetles will fall off the plant right into the bucket and you’ll get more beetles if you do this in the early morning before they start feeding and flying. Several birds (grackles, cardinals, meadowlarks) feed on the adult beetles so encourage birds in your yard.

If you decide to use a lure, place it at least 100 feet away from your garden. Lures attract beetles and if you place one in your garden, you’ll have all the neighbors beetles visiting as well. Find a neighbor who doesn’t garden to host the lures and traps.