It was a branch full of chewed-up leaves that were brought to our office last week. The homeowner was wondering what could be eating the leaves of his young trees. We all know the June bug as the brown beetle that flies around in any outdoor light in the evening and clings to the window screens outside a lighted room. While they don’t bite or sting, they can cause damage to your landscape.
What is not commonly known is the June bug’s propensity to feed on tree and shrub leaves at night. Honestly, how often does one go into the yard late at night with a flashlight to look for bugs on tree limbs? Yet, depending on the severity of the infestation, you may find some chewed-up leaves, some skeletonized leaves, or even a young tree stripped clean of all its leaves come morning.
These adult beetles, commonly called June bugs or May beetles are ½ to 5/8 inches long, and reddish brown. Their very destructive larvae are the common grubworms in the soil. These grub worms are the white “C”-shaped larvae, up to 1 inch long, with cream-colored bodies and brown head capsules. As a true insects, they have three pairs of legs, one on each of the first three segments behind the head.
June bugs are a member of the scarab beetle family. There are more than 100 species of scarab beetles from several genera in Texas that are considered to be white grubs, May beetles, and June bugs. However, the most common is Phyllophaga crinita.
The adults begin to emerge in spring. During adult flights, you can find large numbers of beetles attracted to lights. The first flights begin as early as April and continue into June in our part of East Texas. Females, which are less attracted to lights, tunnel 2 to 5 inches into the soil and deposit their eggs. In 3 to 4 weeks, small grubs (the larvae) hatch from eggs and develop through three stages, called instars, with the first two stages lasting about 3 weeks. The last larval stage remains in the soil from fall through spring. In spring and early summer, white grubs pupate 3 to 6 inches deep in the soil. Adults emerge from pupae in about 3 weeks. There is one generation per year, but in North Texas and colder climates to the north, development may take two years.
June bug grubs are common in Texas turfgrass, particularly Bermudagrass and St. Augustine grass. Feeding large numbers of grubs on turfgrass roots causes lawns to turn yellow and die. This feeding can be so severe that damaged grass can be “rolled up” like a carpet. Grubs also feed on the roots of weeds, vegetable transplants, and ornamentals. In agriculture, they are important pests of forage, corn, sorghum, and sugarcane.
The most severe plant injury is caused by large (third stage or instar) grubs feeding on roots in the fall and spring. There is no doubt that almost every gardener has seen them before. White grubs are frequently encountered tilling garden soil or sifting through the soil underneath damaged turfgrass. Larval stages eat the roots of grasses, vegetables, and ornamental plants.
To control June bug larvae, and ultimately the flying adult beetles, you can purchase a granular soil-applied insecticide labeled for grub control. The best time for preventive control is any time in June, before the eggs hatch. If grubs are already present, curative control via insecticide can be used in late July and early August when grubs are still small. They are much harder to control in late summer when they are full-sized. Water thoroughly following insecticide applications and avoid using a granular product when the foliage is wet.
Never use pesticides on plants other than those listed on the label. As always, follow the product label for all instructions on treatment.
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Cary Sims is the County Extension Agent for agriculture and natural resources for Angelina County. His email address is cw-sims@tamu.edu
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