Property of the United Mites Governn Circular No 82. l-.u.-.l .1 United States Departmenl of Agriqul BURKAU OK ENTOMOLOGY, 1 HOWARD I >nd Chief ..( Hurcau. PUfHOLI I2MUB1 TO MKMKI) CYPRESS IN THE sol III vm> BULP G I 1 1 i 8. B] \. I'. HOPXJKB, , In Charge of Fonti i>>^> and rear their brood.-, and the latter, when fully developed, leave the wood and By to other trees to repeat the pro One of these el.. WOOd-boring beetles is represented by small. short, cylindrical, reddish beetles one-eighth to one-tenth of an inch in length, which are exclusively Bapwood borers. U i rule they are not common in girdled trees, but are abundant in logs from living I The other class is represented by elongate, slender, reddish, cylin- drical beetles three-eighths of an inch in length, which oft.n extend their borings deep into the heartwood and are often common and quite injurious to both girdled and felled trees. One species of this latter class causes more damage, perhaps, than all of the many other insects which have been found boring in the wood of girdled trees. It is known tech- nically as Platypus compositus Say, and may be distinguished from other cypress pin-borers by the English name " girdled-cypress pin- borer," or Pan American Platypus. (See fig. 1.) The facts and evidence of immediate practical importance may be briefly stated as follows: Trees girdled in March, April, October, and November were not at all or but slightly damaged by the girdled-cypress pin-borer, while those girdled in .May, June, July, and September were more or less seriously damaged. There were indications that trees girdled in August were not damaged as badly as those girdled in July Fig. ].— Work of ambrosia beetle? in oak: a, Monarthrum mali and work; b. Platypus compotitus and work: c, bark; rf, sap wood; e, beartwood: /. character of work in lumber from injured log. (Author's illustration.) and September ; also, that trees girdled from December to February were not seriously affected. It was found that local factors and con- ditions had an important bearing on whether or not injury resulted from girdling at given dates. In some localities there was practically no injury to trees girdled on any of the dates. In other localities some of the trees girdled on a given date would be badly damaged while others would show no trace of injuries. The absence of injuries in the former localities may have been due to the presence of a limited number of the insects, or to their being attracted to felled trees in preference to the standing girdled ones, or to some other unknown causes. The attack on individual trees is evidently due to individual differences in the trees themselves, for our general observations indicate quite clearly that certain types and varieties of trees of the same species are more resistant or immune to their inseol enemies while othen are more attractive to them. It i~ well kiuiuii that there i- a marked difference in the individual characteristics of oypress trees in any given locality, and m differenl localities, and thai there is also marked differ- ence among a large number of trees girdled on the same day or time of year in the results obtained. Some will die quickly and dry oul rani illy: smne will remain alive a inueli longer time, the wood remaining moist and becoming discolored; -nine will yield beautifully grained lumber of the highest grade; while others, equally as sound, will yield tough, - grained, ilull lumber "f a l<>w grade. These conditions are do! due entirely to the character < t the work <>f girdling, nor to accident, local influences of soil, etc., l>ut largely to variations which produce more or less distinct, good and poor natural varieties. Therefore cer- tain trees or varieties which prove to be especially attractive to the pin- borer, no matter when they are girdled, may be attacked and more or injured. The girdled-cypress pin-borer must have moist w 1 in which to excavate its burrows and develop its broods of young and will unl attack the trees after they have been dead long enough for the wood to me dry. It evidently prefers to attack the wood of felled gum and cypress. Our observations indicate that living trees felled '" April and August offer specially attractive conditions for infestation l>y this and that it \yill often begin to enter tin- wood within a few days after the trees arc felled. This BUggestS the utilization of felled tree- as traps to attract it away from the girdled ones and at the same time facilitate the destruction of the broods by placing the logs of the trap trees in water after they have become thoroughly infested and before the hroods of adults begin to emerge and fly. To aeconiplish this the trap trees felled in April must he burned or placed in water during the following June and those felled in August treated in the same manner in October. RECOMMENDATIONS. I leneral recommendations for the prevention of insect injury to girdled Cypress may he briefly stated as follows: First. — Conduct the principal girdling operations in March. April, October, and November, or either in the former or latter months as may seem hest from the local conditions and relative value of the product in each locality. October-girdled trees should he felled and lloated or worked up within one year to avoid injury by another class of wood horers which attack trees after they have I. ecu dead one or more years. Second. — In localities where it is known that the insect is abundant and injurious, felled trap trees may he provided in March and April, and July and August, say. one otherwise worthless gum or cypres.- trap tree for each fifty to seventy tree.- to be girdled in the same locality. Tiiii:: 4 3 1262 09216 fc' Third. — If it is desirable to girdle trees at other times during the summer and to utilize trap trees, these latter should be provided a week 3? more ahead of the girdling, and located on the banks of streams, ponds, or pools, where, at the proper time, they can be readily rolled into the water. Fourth. — Trap trees should never be provided unless it is quite cer- tain that they will be placed in the water or otherwise destroyed within two or three months after they are felled and infested by the insects, otherwise they may contribute to a greater multiplication of the insects and increased danger of serious injury to the girdled trees. The adoption and carrying out of these recommendations should be governed in each locality by the personal observations and experience of the operators, based on a study of the conditions resulting from trees girdled at different positively known dates or times of year, and also on a study of the evidences of infestation by the pin-borer in the girdled trees and in the logs, stumps, slash, etc., of cypress, gum, and other trees. These evidences of infestation consist of the greater or less quan- tities of fine, whitish boring-dust on the bark and around the base of the trees and stumps, under the logs, etc., the work of the girdled-cypress pin-borer and its class being distinguished from that of the sapwood borers by the prevalence of short cylindrical sections of adhering dust expelled from the holes. For more detailed information on the habits of wood-boring insects and the character of injuries caused by them in standing and felled trees, lumber, etc., the reader is referred to the Yearbook of the United States Department of Agriculture for 1904, pages 381 to 398. Approved : James Wilson, Secretary of Agriculture. Washington, D. C, December 19, 1906. O