So you're standing in the garden and you hear a loud buzz pass your head. Soon there's another and yet another. Suddenly you feel like you are the target of an all-out air assault. After some patient investigation, you realize the attackers are large, dull, velvety green bugs. They appear to be some sort of morphed May beetle or June bug on steroids - a science experiment gone bad. They seem to fly until they hit something with their poor navigational skills. Put the kamikaze attitude, the buzzing and the size together, and you have a beetle that many people do not like. Here is what you need to worry about when it comes to green June beetles in your home garden.
There some 40 different species of June bugs or May beetles. Adults vary in color from light brown to green to nearly black. Individual species are difficult to identify without examining microscopic characteristics. Generally speaking, adult beetles hide during the day by burrowing into the soil or sod. They emerge from the ground and fly to trees to feed shortly after dusk. They continue to feed all night and return to the soil soon after daybreak. This can result in a tree being stripped of its leaves relatively quickly - in some cases virtually overnight. Though damage may look severe, healthy trees will produce a new set of leaves and be fine in a few weeks. Green June beetle adults are a bit different in that they feed on ripening fruits, including apricots, nectarines, peaches, plums, prunes, apples, pears, grapes, figs, blackberries and raspberries. Larvae feed mainly on humus in the soil but will feed on grass roots from time to time.
Adult June bugs will only be active for a few more weeks. During this time they will be eating, mating and laying eggs. Though June bugs are not the most common species that produce white grubs, it is one that can cause significant damage to turf, trees and shrubs. Killing the adults is not practical as new populations will fly in each night. However, large numbers of green June beetles can cause some damage to our crops. A number of general-use insecticides can be used to discourage their feeding, including Sevin and malathion. Sevin has a two-day waiting period between spraying and harvest on sweet corn, and it has a three-day waiting period on peaches. However, there is a seven-day waiting period for Sevin on blackberries; therefore, malathion (one-day waiting period) may be a better choice.
To control future populations, begin applying grub killers now. Lawns most likely to be damaged are those with streetlights or other lights that attract the beetles and those with moist soil. If we do not have sufficient rain to keep all lawns moist, the female beetles will prefer irrigated areas where it is easier to dig and lay eggs. However, with the recent rains, almost any turf area is a potential host site. Traditional grub insecticides such as Dylox are normally applied in late July after the grubs are present or as a rescue treatment once damage is seen. Products that contain Merit (imidacloprid) or Mach 2 (halofenozide) are considered grub preventers. Actually, neither product prevents grubs, but rather they kill grubs when they are quite small and long before they cause damage. Merit and Mach 2 are safer to use around pets and humans than other grub killers. Merit can be found in Bayer's Season-Long Grub Control and Grub-Ex. Mach 2 is the active ingredient in Kill-a-Grub. Remember all grub products must be watered in before they are activated. As always, read and follow the label directions.