June Bugs Lead to Lawn Grubs

Summer is the time when people begin to notice large bright green beetles in their yard, called June Bugs or Green June Beetles. Adult and larval feeding on economic crops causes some financial loss; however, the grubs tunneling for feed and the adults' burrowing into the soil each night cause more serious destruction. The tunneling uproots young plants. The many exit holes of the adults and larvae resemble ant hills and mar lawns and golf course greens.

The Green June beetle is 15 to 22 mm long with dull, metallic green wings. Its head, legs, and underside are shiny green, and its sides are brownish yellow. The green June beetle occurs in the eastern United States westward to Kansas and Texas. Green June beetles prefer ripening fruits of many plants. The grubs feed on decaying organic matter in the thatch and root zone of many grasses, as well as on the underground portions of other plants such as sweet potatoes and carrots.

Only 1 year is required for these beetles to complete their life cycle. They overwinter as grubs that may become active on warm winter days. They increase their activity in the spring, and in June pupate in earthen cells several centimeters underground. The pupal stage lasts about 18 days; adults appear in July and August. In mid-summer, adults lay eggs underground in earthen balls. Each female lays 60 to 75 eggs over a span of about 2 weeks. When the egg is first laid, it is pearly white and elliptical (1.5 mm by 2.1 mm). It gradually becomes more spherical as the larva inside develops. About 18 days after the eggs are laid, they hatch into small, white grubs. The newly hatched larva is 8 mm long and grows to a length of about 40 mm. Whitish with a brownish-black head, the grub has conspicuous brown spiracles along the sides of its body. The larvae molt twice before winter. The third larval stage lasts nearly 9 months, after which pupation occurs. At night, the larvae may be found on the ground crawling on their backs. This curious form of locomotion is peculiar to the green June beetle.The brown pupa, approximately the same shape as the adult, becomes metallic green just before the adult emerges. It is about 15 mm long and 15 mm wide.

Sections of turf 30 sq cm (about 1 sq ft) and 5 to 10 cm (about 2 to 4 inches) deep should be examined for green June beetle grubs. On golf course fairways 10 to 20 samples of this size should be taken. If examination reveals an average of 6 to 8 larvae per 30 sq cm, treatment is usually necessary. Do not apply manures or organic fertilizers during the summer months since adults are attracted to these materials.

The best time to control Green June Beetles is mid-August until early September; by mid-September the best time for control is already past. If you choose to use a carbaryl product such as Sevin, apply it to the soil surface but do not water it in. Another effective product is the chemical diazinon (Spectracide); water the grass thoroughly after application if you use this product.

As in all chemical pest control operations, caution is necessary. Heed the pesticide label and follow instructions closely. After application of insecticides to the lawn keep people and pets off of the area for the number of hours specified on the label. Never clean sprayers or dump pesticides into sewers, in or near storm drains, streams, rivers, lakes, or ponds.

Recommendation of specific chemical are included as a convenience to the reader. The use of brand names does not imply endorsement of the product by the N. C. Cooperative Extension Service nor discrimination against similar products or services not mentioned. Individuals who use agricultural chemicals are responsible for ensuring that the intended use comples with current regulations and conforms to the product label.

From Wikipedia.org:

Phyllophaga is a very large genus (more than 260 species) of New World scarab beetles in the subfamily Melolonthinae. Common names for this genus and many other related genera in the subfamily Melolonthinae are May beetles, June bugs, and June beetles. They range in size from 8–25 mm and are blackish or reddish-brown in colour, without prominent markings, and often rather hairy ventrally. These beetles are nocturnal, coming to lights in great numbers. The adults are chafers, feeding on foliage of trees and shrubs. They may cause significant damage when emerging in large numbers. The larvae (called white grubs) feed on the roots of grasses and other plants. The insects pupate underground in the fall and emerge as adults the following spring. To test for the presence of these beetles, drenching an area of lawn with a wet substance will cause larvae to emerge at the surface. The adult beetles are very clumsy, both on land and in the air.

Flies in the family Pyrgotidae are endoparasitoids of these and related beetles. The female flies pursue the beetles in flight, laying an egg on the beetle's back under the elytra where the beetle cannot reach it. The egg hatches and the fly larva enters the body cavity of the beetle, feeding on and eventually killing the host before pupating. Wasps in numerous families are parasitoids of Phyllophaga grubs, including Pelecinidae, Scoliidae, and Tiphiidae.

The generic name is derived from the Greek words phyllon, which means "leaf", and phagos, which means "eater", with a feminine ending.

Adult chafers eat the leaves and flowers of many deciduous trees, shrubs and other plants. However, their fat, white grubs (reaching 40–45 mm long when full grown) live in the soil and feed on plant roots, especially those of grasses and cereals, and are occasional pests in pastures, nurseries, gardens, and golf courses. The injury consists of poorly growing patches that quickly turn brown in dry weather. The grubs can be found immediately below the surface, usually lying in a characteristic comma-like position.

The grubs sometimes attack vegetables and other garden plants, e.g. lettuce, raspberry, strawberry and young ornamental trees. Injury to the roots and rootstock causes small saplings and tender tap-rooted plants like lettuce to wilt suddenly or to show stunted growth and a tendency to shed leaves prematurely. Plants growing in rows are usually attacked in succession as the grubs move along from one plant to the next. Chafer grubs feed below ground for 3–4 years before changing into adult beetles.