Japanese beetles are believed to have been introduced to the United States in 1916. Unlike in Japan, where they have a variety of natural predators, these beetles have no predators here in the States. As such they have become a serious invasive pest, with incredibly damaging feeding habits. They are around a half inch in both length and width, with a copper-colored body and iridescent green head. They may also appear to have white spots or hair around their sides.
Adult Japanese beetles spend their days eating, mating, and laying eggs. A female beetle will lay between 40 to 60 eggs in her month-long lifespan. These eggs take around two weeks to hatch. Once the larvae hatch, they feed on fine organic matter, taking in steadily more coarse matter as they grow into their grub stage. Larvae will hibernate through the winter, and pupate into adults typically within a month of waking. The adult beetles feed on leaves, leading to above ground damage to plants as well.
Since its accidental introduction in 1916, the Japanese beetle has slowly made its way across the US, and cause serious stress to many homeowners. Larvae and grubs of the beetle feed on plant roots, with lawn grasses particularly susceptible. Upon adulthood, the beetles then skeletonize leaves, meaning that they eat the plant matter of the leaf but leave the veins of the leaf alone. Unlike the larvae, they feed on a wide variety of plant leaves, with many of these being common or popular crops. Some of these include strawberries, hops, tomatoes, pears, and corn, but there are many others. When the beetles feed, they release a pheromone, a non-detectable scent, to attract other beetles to the area. With their skeletonizing feeding habits and their pheromone use, they can cause severe damage to plants and gardens in a very short amount of time.
Controlling Japanese Beetles
The best time to apply insecticides for grubs is from mid-July until end of September. Granular insecticide applied to the soil with a spreader is usually the best insecticide for Japanese Beetle Control. Often times, we receive calls because of the damage they do during their adult stage. We can control these areas with our spray treatments.
Did You Know?
As of 2014, Japanese beetles are causing problems in mainland Europe as well!