August 15, 2003 at 10:59 a.m.
There is the Japanese beetle and the false Japanese beetle. Although both beetles are the same size (7/16 inches long) you can distinguish between them. Japanese beetles have an emerald green prothorax (the first area behind the head) and coppery brown wing covers and generally looks shiny. There are five small patches of white hairs on each side of the abdomen and two on the tip of the abdomen.
In contrast, false Japanese beetles are duller with a dark brown (with a hint of green) prothorax and tannish to brown wing covers. It completely lacks any white patches of hair on the side or tip of its abdomen.
Both beetles first emerge late in June or early July. While Japanese beetles are active through August, false Japanese beetles are present for only a few weeks and are generally gone by the end of July. They both like the leaves of roses, morning glories, cucumbers, and the list goes on. If you feel that it is necessary to use an insecticide, I suggest permethrin or carburyl (Sevin). In looking at a pamphlet put out by Ortho, I see they have several suggestions. In any case, follow the directions on the label. Also, be sure that the product you use can be tolerated by the plants. An example would be roses where some chemicals could do more damage then the insect itself.
A beetle that is far less destructive but certainly a nuisance is the picnic or sap beetle. This is the beetle that is found in your raspberries, sweet corn, or any fruit or vegetable that is over ripe. I never had a problem with picnic beetles on my raspberries until this year. Although I have everbearing raspberries, I always cut them to the ground so I only get a fall crop. However, this year I have some summer bearing raspberries and picnic beetles.
The picnic beetle which is a type of sap beetle, attracted to any fermenting or sour smell. They like overripe and rotting fruits and vegetables, especially corn, melons, berries and tomatoes. Once they are in your garden they can also attack product that is ripening.
The best way to control the picnic beetle is through proper sanitation. Avoid attracting them by harvesting fruits and vegetables as soon as they ripen. Remove any overripe or damaged produce and throw it away or bury it to make your garden less inviting to the beetles. Insecticides are usually not effective in keeping picnic beetles away. The insecticide residue left on the plant prevents you from harvesting any fruit or vegetable immediately. By the time it is safe to pick your crop, new picnic beetles will have returned. If you must use an insecticide, choose a product with as short an interval between application and harvest as possible. Malathion is a good choice and follow label instructions very carefully.