2IO Forestry Quarterly. 



is more or less conspicuous and becomes apparent even to the lay- 

 men as soon as it is well under way. These large invasions rep- 

 resent one class of infestation. There is another source of di- 

 rect insect loss which is caused by a different class of infesta- 

 tion. Annually throughout the forest, trees will die, either singly 

 or in small groups. When these scattered dying trees are no- 

 ticed, they are seldom considered an important item of damage. 

 Quite often they are considered as only the necessary annual 

 deadening of overmature trees. The total amount of loss in 

 this type of infestation is much underestimated. The damage 

 is very easily overlooked in the mixed stands which we find on 

 many of our California forests. Where one species of tree alone 

 is suffering from insect attack, the dead and dying individuals 

 are sometimes hidden by the surrounding green foliage or resis- 

 tant species. 



A careful reconnaissance and estimate of insect loss is needed 

 on all our National Forests. The results of such a reconnais- 

 sance will undoubtedly show that the greatest loss that our West- 

 ern forests are now suffering does not arise from the few con- 

 spicuous local outbreaks, such as are now in progress in the lodge- 

 pole pine on the Lassen National Forest, but in the sustained an- 

 nual loss of scattered merchantable trees. Although only a 

 few trees may die in a season on the same section, still the dead 

 timber which accumulates in a period of years amounts to a 

 rather startling total. Much of this dead material however is 

 burned up by periodical fires which destroy all evidence of in- 

 sect attack. 



The annual rate of dying timber may vary greatly in different 

 situations and in some localities this scattered infestation be- 

 comes so serious as to approach the character of an invasion. A 

 study to determine just how serious may be the loss from this 

 type of infestation was recently made upon the Klamath Na- 

 tional Forest by the Forest Service under the advice of Dr. 

 Hopkins of the Bureau of Entomology. An area consisting of 

 about four thousand acres was selected near the Klamath River 

 in Township 46 North, Range 8 West, Mount Diablo Meridian, 

 which contained representative sections. In places the dying 

 of groups of trees has been so persistent that noticeable open- 

 ings have appeared in the stand. The elevation of the area varies 



