All plants are wonderful. However, it is highly unlikely to find a plant that has absolutely no insect problems. This year we have been seeing a couple of unusual beetles wreaking havoc in our vegetable gardens and they can be found on our trees and shrubs as well. Japanese Beetles and Green June Beetles have been more problematic in southeastern Nebraska this year than most other years.
Japanese beetles are an invasive insect from Japan, where it is not a major pest due to the natural predators found there. This pest was first found in the United States in a New Jersey nursery in 1916 and was likely introduced in infested iris bulbs from Japan. Since this initial introduction, Japanese beetle populations have steadily expanded westward.
Japanese beetles are problematic insects as both larvae and adults. The larvae are one of the four most common types of white grubs found in Nebraska. As a white grub, larvae feed on the roots of our grass, causing large brown dead spots in the turf that are easily lifted up like a rug from the floor. Adult Japanese beetles are 7/16 inch-long, metallic green beetles. The elytra, or wing coverings, are copper. These beetles can be distinguished from similar looking beetles by the six tufts of white hair along both sides of the abdomen. As adults, Japanese beetles feed on over 300 species of plants including trees, shrubs, fruits, vegetables, field crops, weeds, and other ornamental plant species. Some of their favorite food plants are roses, lindens, and grapes amongst others. Adult beetles feed on the foliage, flowers, and fruits of these plants. They feed on the upper surface of the leaves and cause a skeletonized pattern to the leaf where the veins of the leaf are often left behind but the rest of the leaf is chewed away. In some cases, they will consume the entire leaf. This can stress the plants, and in high populations of beetles can even kill the plant.
Green June beetles are often being found this year as opposed to other years. They are very large, usually more than one-inch in length. They are dull green with some brownish coloration to the elytra and a tan border along the margins of their elytra, which are the hard wing coverings on a beetle. Green June Beetles will feed on ripe fruits and vegetables like tomatoes, corn, and grapes. They will feed on the fruits and the leaves of the plants and as an immature, they are also a white grub species.
These 2 green beetles can be controlled through multiple methods. As larvae, they are best controlled with insecticides applied to the lawn in the months of May, June, and July. There are many different options available including the most common grub control, Merit which contains imidacloprid. Pesticides can be used on the adults in plants, however, be sure to avoid use of pesticides directly on the flowers of these plants to avoid harming pollinators. Imidacloprid, sevin, eight, or other general insecticides can be used on trees and shrubs to control the beetles. In low adult populations, you can hand pick the beetles off of plants and throw them into a bucket of soapy water to kill them and not harm any pollinators.