Insect of the Month: Green June Beetles

Photo of a Green June Beetle. Photo by Mike Merchant.

Green June Beetle. Photo by Mike Merchant.

It’s the time of year that green june beetles are spotted in large clusters around Central Texas.

According to Extension Program Specialist Wizzie Brown, these beetles are known by their velvety green appearance and measure about one inch long and one-half inch wide. The beetle’s top is a dull green with yellow-brown markings on the wings and the underside is bright, metallic green with yellow-orange markings. The larvae, usually called grubs, are creamy white and shaped like the letter C with well-developed head capsules and legs and can grow over an inch in length.

Brown also said the adult beetles are large and conspicuous and like to eat thin-skinned fruits (such as grapes, peaches, figs and others) or fermented fruits and some flowers. Adults may also be found on trees that are oozing sap, but the beetles are not causing the sap to ooze from the tree.

Larvae feed in the soil and eat plants such as turfgrass, vegetables and ornamental plants. Grubs often will emerge from the soil at night and crawl on their backs instead of using their short legs. The grubs also may cause small mounds of soil on the turf that may be mistaken for fire ant mounds or earthworm castings.

To check for grubs, which are the damaging stage, Brown recommends cutting several 4″ x 4″ soil sections in different areas of the turf and look in the root zone and soil for presence of grubs. It is possible to have grubs in the turf and not see any damage. If a turf is kept healthy, then it can withstand some damage from insects.

Brown recommends trying nematodes or pesticides for treating the grubs. When choosing nematodes, be aware that they require moist soil to move and parasitize prey. If the cities people live in are under watering restrictions, she said that the above method may not be a feasible option. Pesticides come in granular or liquid formulations with systemic (i.e. the active ingredient imidacloprid) or contact (i.e. the active ingredient cyfluthrin) modes of action.

Contact products need to come in contact with the grub for it to kill the insect, so it will require watering in to carry any pesticide to the soil where the grubs are located. Systemic products also require watering in, but the turf will take up the active ingredient into the roots and the grub will get a dose when it feeds on the turf. Granular products should be applied with a properly calibrated spreader and then watered in. Always read and follow all label instructions, she said.

For more information about green June beetles, see the Field Guide To Common Texas Insects website at http://texasinsects.tamu.edu/bimg142.html or the Green June Beetle Biology, Damage and Control fact sheet at https://insects.tamu.edu/extension/publications/epubs/eee_00044.html.

For additional help on control and management, contact your local Texas A&M AgriLife Extension Service agent.

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