The small number of requests for information on insect pests of northern tree nuts received in the Bureau of Entomology and Plant Quarantine is a strong indication that such pests are of little concern to northern nut growers. This is fortunate, because intensive, all-season spray programs, such as are necessary to produce most other crops without serious losses due to insect injury, are laborious and expensive and not always as effective as desired. However, as your acreage is increased and as your trees become older and larger, insect problems are likely to increase in number and intensity and require more of your thought and attention. A somewhat similar situation prevailed in the pecan industry at one time in the South. I well remember the statement of one of the larger pecan growers in Louisiana to the effect that all the pleasure of growing pecans would be gone the day he had to start spraying to control insects and diseases. Only a short time later it became necessary for him to initiate a regular spray program. He still took great pride in growing pecans, however. It is well, therefore, for you to watch your trees closely for insect damage and keep informed concerning the habits and control of the species that show up in your plantings or in those of your neighbors. Because of the scattered nature of the northern nut industry, the small size of most plantings, and the more pressing demands for information on the control of pests of more intensively planted crops, it has not been possible for the Bureau of Entomology and Plant Quarantine to give attention to many of the pests of northern nuts. A great deal of work has been done on the pests of pecans in the South, and some work on those that attack filberts and chestnuts. In addition, some of the pests with which you are concerned, or others similar to them, are receiving attention in connection with studies of pests of tree fruits. The results of these studies will give you up-to-date information applicable to your particular problems. The timely use of insecticides is the most effective means of combating most injurious insects, but if spraying is not possible, other methods can often be used to prevent or reduce damage. A great many new insecticides have become available during the last six or seven years. Work with them has resulted in the development of treatments effective against a number of pests for which there was formerly no known means of control and markedly more effective treatments for the control of others. It is my purpose to bring to you as much of this new information as is applicable to your problems. Leaf-feeding Caterpillars The fall webworm[3] and the walnut caterpillar[4] are the leaf-feeding caterpillars most commonly reported as attacking northern tree nuts.