Insect of the Week: the May/June beetle

Adapted from pages 466-468 of Garden Insects of North America:

May/June Beetles (Phyllophaga spp.) are among the largest of the white grubs, typically about 3/4 inches to 1 inch long and stout-bodied. Adults are generally chocolate brown to nearly black. More than 200 species occur in North America, with about 25 reported to damage turfgrasses, garden plants, and field crops. The adults are active at night and may be seen careening around porch lights and bouncing off screens, often in late spring. The beetles feed on the foliage of various trees and shrubs, with oak a preferred host for many species, but this rarely results in any significant injuries. Much more significant damage results from the white grub larvae, which chew on plant roots. Grasses are most commonly damaged, but larvae can seriously injure roots of young trees and shrubs planted in grassy areas.

 In northern areas, May/June beetles often have an extended life cycle that requires 3 years to complete. With these species, eggs are laid in the soil in May or June, and a limited amount of feeding takes place by young larvae during the first season, before they migrate downward for winter. They return to feed on roots and grow rapidly during the second season, producing most damage at this time. In the third year there is some additional feeding before the insects pupate in a belowground chamber. They transform to adults in late summer and early fall, ready to emerge the following year.

An adult May/June beetle. Photo credit: David Shetlar

Variations of May/June beetle life cycles occur, and in the southern U.S. many species complete development in a single season. Phyllophaga crinita, an important species in Texas, and P. latifrons, found in most Gulf States, have this habit. They commonly damage St. Augustinegrass, bermudagrass, and buffalograss.

Garden Insects of North America: The Ultimate Guide to Backyard Bugs
Second Edition
By Whitney Cranshaw & David Shetlar

This second edition of Garden Insects of North America solidifies its place as the most comprehensive guide to the common insects, mites, and other “bugs” found in the backyards and gardens of the United States and Canada. Featuring 3,300 full-color photos and concise, detailed text, this fully revised book covers the hundreds of species of insects and mites associated with fruits and vegetables, shade trees and shrubs, flowers and ornamental plants, and turfgrass—from aphids and bumble bees to leafhoppers and mealybugs to woollybears and yellowjacket wasps—and much more. This new edition also provides a greatly expanded treatment of common pollinators and flower visitors, the natural enemies of garden pests, and the earthworms, insects, and other arthropods that help with decomposing plant matter in the garden.

Designed to help you easily identify what you find in the garden, the book is organized by where insects are most likely to be seen—on leaves, shoots, flowers, roots, or soil. Photos are included throughout the book, next to detailed descriptions of the insects and their associated plants.

An indispensable guide to the natural microcosm in our backyards, Garden Insects of North America continues to be the definitive resource for amateur gardeners, insect lovers, and professional entomologists.

  • Revised and expanded edition covers most of the insects, mites, and other “bugs” one may find in yards or gardens in the United States and Canada—all in one handy volume
  • Features more than 3,300 full-color photos, more than twice the illustrations of the first edition
  • Concise, informative text organized to help you easily identify insects and the plant injuries that they may cause


This post is part of a series, explore additional posts here<< Insect of the Week: the Emerald Ash BorerInsect of the Week: the Great Spangled Fritillary >>