The 1947 season marks the fourth year of the experimental use of DDT for control of the chestnut weevils. During these years our knowledge of the spray and how best to use it has been advanced by conducting laboratory and field tests. Unfortunately, few chestnut orchards now exist in the Eastern States, and the scattered plantings consist mostly of a large number of Asiatic seedlings, some of which had to be top-worked to other Asiatic species and varieties. Many of these trees are grown for ornamental, shade, or timber purposes rather than for nut production. Owing to these conditions and to a series of spring frosts since 1945, it has been impossible to conduct insecticide experiments on an adequate basis of replicated plats. Although much is to be learned regarding time of application of the sprays and the proper dosage, the use of DDT can be recommended as a standard practice, because it has proved highly valuable in protecting chestnut trees from heavy losses due to the chestnut weevil. It is the purpose of this paper to discuss some of the experiments that have been made with DDT and the observations made on the time of egg deposition. +Nature and Extent of Injury+ The worms attacking chestnuts are the larvae of two very similar species of weevils, one larger than the other. The adults are medium-sized beetles having extremely long, slender beaks. With these they drill through the husk of the nuts, making openings through which they insert their eggs into the nuts. From these eggs the familiar worms develop. Weevil injury varies greatly in different chestnut-growing localities. It is not unusual for 50 to 75 percent of the nuts to be wormy, and often infestation reaches 90 to 100 per cent. The small weevil does the most damage, but there are indications that this may not always be true. Because the mouth parts of the adult are situated at the end of an extremely long and slender beak, it can obtain most of its food from beneath the surface of the host plant. For this reason, stomach poisons applied to trees have not been eaten by these weevils, and hence have been of no practical value. As DDT kills by contact, it is necessary only for the body of the insect to come in contact with DDT. +Life Histories of the Weevils+