~Life history:~ The Japanese beetles in the adult stage are in evidence here from late June to late September, or, roughly, for the summer season. The adults lay their eggs in the soil, mostly in lawns, mowed grassy fields and pastures. The adults die but the eggs give rise to tiny, bluish-gray larvae which feed chiefly on grass roots. The larvae grow through the fall and spring, and, if more numerous than about 40 to the square foot in September, or about 25 in April and May, can cause severe lawn damage.

MR. CORSAN: That's the stage when the pheasants and starlings eat them.

DR. ADAMS: Yes, in the grub stage.

MR. CORSAN: I see thousands of starlings gorging themselves.

DR. ADAMS: Yes, scratching birds, crows and skunks can take them out; the starlings make a hole the size of a pencil point to do so. In our survey areas grub populations sometimes seem to drop rapidly in May, when the birds are feeding their nestlings. In June, the surviving larvae mostly change into pupae, and by July they are appearing as beetles. From the lawns and grassy fields they readily fly to weeds, shrubs, grapevines and trees. They fly at least a few hundred yards, if need be, to find their host plants. Well kept, sunny, lawns with good, moist soil, which carry 40 grubs to the square foot in the fall may still have plenty at transformation time in early summer. A lawn of 5,000 square feet could thus produce 100,000 beetles. Yards, roadways and pastures commonly produce as many as six beetles to the square foot, which means a quarter million to the acre.

~Chemical control in the grub stage:~ In New York we suggest that on a home property the more valuable sections of permanent lawn be grub-proofed with chemicals as soon as there are 5 to 10 grubs to the square foot. This grub-proofing has two effects: (a) it stops beetle production from that lawn, and (b) it prevents the lawn grass being damaged by the grubs of this and other annual grub species and by the birds and animals, including moles, which damage grubby turf. For grub-proofing I prefer to use chlordane. It may be applied in a spray, at 8 ounces of 50% wettable powder to 1,000 square feet, or it may be purchased in the more bulky 5% form and applied dry with a two-wheeled lawn fertilizer spreader. For each 1,000 square feet I take 5 pounds of 5% chlordane and, since it tends to clog the spreader, I mix it in a cardboard drum with 5 pounds of a dry, granular material such as the activated-sludge fertilizer known as "Milorganite." The ten pounds of mixture is then spread on the 1,000 square feet, half east and west, half north and south.

If applied in the fall or early spring there will be no beetles coming out in July and no grubs for several years. DDT at 6 pounds of 10% DDT to 1,000 square feet will give an even longer grub-proofing effect. Our plots so treated in 1944 are still grub-free. The possible trouble with DDT is that it is too nearly permanent, and if you should plow up a piece of lawn treated with it and try to raise tomatoes or strawberries, you might find the soil too toxic.

~Biological control in the grub stage:~ The chemical grub-proofing of the sunny parts of the front or main lawn on a property is desirable for the reasons stated, but it does not usually stop more than a fifth of the beetle production around the property, because there are usually plenty of neighbors' lawns, pastures, public grounds, and other beetle-producing turf areas nearby. How are you to reduce the beetle crop on these places, mostly on ground you don't control? Here is where biological control comes in, something which I feel will appeal to you in this group. The parasitic insects known as spring Tiphia, imported from the Orient and well established on hundreds of estates, golf courses, and cemeteries around Philadelphia and New York, may be introduced in your vicinity when grubs reach about 5 to the square foot. The parasites, which are like flying ants, appear above ground in spring and feed on honey-dew. The female burrows in the soil and attaches her eggs singly to Japanese beetle grubs. A maggot hatches and consumes the grub. I have charge of the distribution of these parasites in New York. I like to liberate at least one colony in each village or town division. Some of you may help me plan the liberation for your vicinity, possibly on a cemetery near your place. The colonies enlarge to about a square mile in 10 years, and may cut beetle production by 50%.

Another biological agent which can be added to grub-carrying turf is the bacterium causing Japanese beetle grubs to turn milky white and die. A powder is made from diseased grubs and talc and this milky disease spore inoculum is applied with a teaspoon in dots or spots over the turf. The important point is that the spore powder must be used on a plot where there are grubs to get the disease, and not on chemically grub-proofed soil. Milky disease spore powder is sold under three brand names, "Japidemic," "Japonex" and "Sawco-Japy." One-half pound, suitably applied, will cost you about $2.50 and be an act of good citizenship, for the disease slowly spreads to any grubby soil in surrounding properties. I can supply addresses of the producers and detailed reprints of my studies.

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