WHITE GRUBS

A, Adult beetles feeding on "bite oak leaf. B, Grub feeding on roots of young corn plant. C. Life stages including a, eggs in earth cells; h, fully developed grub; and c. pupa in earth cell. (All about natural size.)

WHITE GRUBS

White grubs are the young or immature stage of the common brown May beetles, of which there are more than 100 species. The grubs feed on the roots of bluegrass, timothy, corn, soybeans, and several other crops, and on the tubers of potato. They sometimes ruin bluegrass pastures in the Northeastern and North Central States and may be serious pests of nursery plantings. The adult beetles eat the leaves of oak, ash, hickory, poplar, elm, willow, locust, blackberry, pine, walnut, and other trees. Most of the injurious species have a 3-year life cycle and cause serious outbreaks in certain years.

The pearly-white eggs are deposited in the spring 1 to 8 inches deep in the soil. They hatch 3 or 4 weeks later into young grubs, which feed on decaying vegetation and even on living roots. The grubs do their greatest injury in their second year but in their third year may sometimes damage early plantings.

Control: Populations of white grubs can be reduced by planting the deep-rooted legumes such as sweetclover, alfalfa, and various clovers, which are unfavorable to these insects, in rotation with more susceptible crops, such as timothy and small grains. The use of legumes is most effective if they are planted in the years of major beetle flights. A system of renovating bluegrass pastures badly infested with white grubs has proved beneficial. The sod is thoroughly torn up during the late fall or early spring, treated with lime and fertilizer as needed, and sown in the spring with a seed mixture consisting mainly of legumes. These soon provide good pastures and are gradually replaced by the original bluegrass.

Lawns and golf courses infested with white grubs may be treated with 10 pounds of lead arsenate per 1,000 square feet of area. Chlordane has also given satisfactory control when applied to turf on golf courses at a dosage of 10 pounds of the technical material per acre in the form of a 5-percent dust, or as a spray preparation.

The inclusion of other crops, such as the clovers or alfalfa, in the rotation is recommended to combat white grub damage to soybeans or to corn following soybeans.

A spray prepared by mixing 2 pounds of lead arsenate, 1 pound of wheat flour or 8 fluid ounces of raw linseed oil, and 25 gallons of water has been used successfully to destroy the adult beetles feeding on tree foliage.

Keep small children and domestic animals away from turf treated with lead arsenate or chlordane until the insecticide has been washed into the soil.