Symptoms and damage
Adult Japanese beetles are about ½ inch in length and
coppery-brown in color with metallic green heads. They emerge from the soil and
feed from May to August. They lay their eggs in the soil. Grubs hatch from the
eggs and feed on grass roots. As the weather cools, the grubs move more deeply
into the soil, to overwinter.
Both adult beetles and their larvae (grubs) can seriously damage
plants as a result of their feeding. Adult Japanese beetles eat flowers and
skeletonize leaves (eat leaf tissue between the veins, resulting in a lacy
skeleton remaining). The grubs feed on the roots of plants, especially on the
roots of grasses.
Multiple approaches are necessary
for controlling Japanese beetles. Adults can be removed by handpicking and
destroyed. Japanese beetle traps are available commercially or can be homemade.
They may be effective at reducing adult populations.
Keep traps at least 50 feet from
the crape myrtle tree or you may create more of a problem by attracting them to
the area. Milky spore,Paenibacilluspopilliae, is a
disease-causing bacterium that is effective against grubs of Japanese beetles
but not the adults. It is commercially available for homeowner use. Many
products containing carbaryl, neem oil, cyfluthrin, permethrin, lambda
cyhalothrin or acephate are labeled for use by homeowners against Japanese
beetles on crape myrtle. Soil drenches of imidacloprid in the spring will
control Japanese beetles and last longer within the plant to prevent future
infestations by additional pests .