By Scout Nelson
Japanese beetles are becoming a growing concern for homeowners and gardeners across parts of South Dakota.
These invasive insects feed-on many different plants and can quickly damage flowers, fruits, trees, and lawns during the summer growing season.
SDSU Extension Entomologist Dr. Jonathan Lundgren explained that Japanese beetle populations have remained low in some locations during the last 10 years, but larger groups have recently been found in his garden in Brookings.
The beetles are easy to recognize by their shiny bronze-green head and thorax, reddish-brown wing covers, and white tufts of hair along the sides and back of the abdomen.
Japanese beetles are not new to South Dakota, but they are still uncommon in many communities. They are most common in the southeastern part of the state and along the Interstate 29 corridor. This invasive insect has gradually moved west since it was first discovered in New Jersey in 1916.
Adult Japanese beetles feed on more than 300 plant species. They often gather in large groups and remove the green tissue from leaves, leaving only the veins behind. This type of feeding is called skeletonizing. The insects also feed on flowers and fruits, causing additional damage.
Favorite plants include roses, grapes, linden, apple, crabapple, cherry, plum, birch, elm, raspberry, currant, basil, hollyhock, Virginia creeper, marigold, soybean, and corn silks. While damage usually affects the appearance of healthy plants, heavy feeding can destroy rose blooms, fruits, vegetables, and sometimes slow early plant growth.
The larvae live in the soil as white grubs and feed on grass roots. This feeding creates brown patches in lawns as the grass begins to die. Japanese beetle grubs can be identified by their small V-shaped hair pattern at the end of the body. The best time to manage grubs is from late July through mid-August, when they remain small and feed close to the soil surface.
Gardeners should begin management as soon as adult beetles appear. Hand-picking beetles and placing them into a container of soapy water works well for small infestations. Larger populations may require insecticides if valuable plants receive severe damage. Products should always be used exactly as directed on the label, especially when plants are flowering to protect pollinators.
Photo Credit: pexels-chris-f
Categories: South Dakota, Crops, Fruits and Vegetables