June 24, 2010 at 9:33 a.m.
The Japanese Beetle (Popillia japonica), is said to have arrived in the United States around 1916 when they were accidentally shipped in with Iris roots imported from Japan. They are members of the Scarabaeoidea family and have veracious appetites for over 300 varieties of plants. Among their favorites are roses, birch trees, grapevines, fruit trees, and common lilac. Though each beetle does not eat much all by itself, it is the large group feedings that cause plants to be overwhelmed and foliage to be skeletonized. Japanese Beetles will often hide within the petals of roses as they eat their way out.
They are identified by these specific features: They are approximately 3/8 inches in length. The front of the beetle is dark metallic green. Its wing covers are a metalic dark tan. The beetle has two small patches of short white hairs on its rear, and five white hair tufts along each side of the dorsal abdomen. These patches are key characteristics for identification. If it does not have these patches, but has the other color traits, then it may be the false Japanese beetle.
And it's not just the adult beetles that can cause so much damage. In it's grub stage, it feeds on turf grass roots and reduces the ability of grass to take up enough water to withstand the stresses of hot, dry weather. As a result, large dead patches of grass develop in grub infested areas. The sod on these dead patches can be rolled back like a carpet to expose the grubs and the lack of turf roots. Early recognition of the problem can prevent this destruction.
The adult Japanese Beetle emerges from the soil in late June and July and begins it's feeding frenzy. Females live only a few weeks and during that time they return late each day to the turf to lay eggs. Eggs hatch in July and the grub is full grown by August. The grub digs in deep for the winter months and then moves upward as the soil temperatures warm in spring.
Non chemical control of the Japanese Beetle is most often recommended. This simply means that as soon as you notice them in the garden, remove them off the plant and drop them into a bucket of soapy water. This may become quite a chore for those first weeks when infestation is heavy. Chemical controls are another option by using insecticidal products containing permethrin and malathion among others. Look for products that list Japanese Beetles on the label. Japanese Beetle traps may not be the best choice as they tend to lure many more into the area than they actually trap.