Japanese Beetles on a Crab Apple Tree

Identification

• The adult Japanese beetle is less than 1 inch long and sports a metallic-green color accentuated by copper-brown wings and patches of white hairs. The larvae of the beetle are six-legged white grubs that measure approximately 1 inch in length. The adults feed on the upper surface of leaves of the crab apple tree, munching away tissue between the veins and skeletonizing them to a point that the leaves begin to resemble a patchwork of lace.

Lifespan

• Female Japanese beetles deposit between 40 and 60 eggs a depth of 2 to 3 inches in the soil, normally in moist, grassy areas. Upon hatching, the beetle grubs spend 10 months living in the earth before emerging as adults in June. They survive between 30 and 45 days, during which they feed, mate and deposit a new generation of eggs. The adult Japanese beetle is mobile and able to fly several miles to infest new crab apple trees.

Control

• The beetle releases a pheromone that draws other beetles to the tree, so control of the population when it is still small is vital. Simple removal of the Japanese beetle by hand is an option -- drop the beetle into a tub of soapy water to kill it -- although this technique obviously will not suffice when large numbers are present, especially in the upper reaches of a tree. Mechanical and chemical control options are also available.

Traps

• Pheromone-based traps are effective in capturing the adult Japanese beetle. However, they provide no protection against grubs. For traps to work properly, they must be deployed immediately in June when adults begin to emerge from the ground. It is important to remember that the female will lay her eggs within seven to 10 days of popping from the earth. Trap deployment should continue into September and October to capture all available adults.