88 THE SCOLYTID BEETLES. 



without burning, is sufficient to kill the broods of this species. If 

 large numbers of lightning-struck trees, and those injured by storms 

 or otherwise, become infested during the summer, they should be 

 barked before the succeeding July. The felling and barking of newly- 

 attacked trees during August and September is not to be recommended 

 for this species. 



This species, unlike D. ponderosse, is attracted to injured and 

 felled trees, and therefore may be trapped to a limited extent in trees 

 felled during July and August, and may be destroyed by removing 

 the bark any time between October and the following July. This 

 may or may not provide sufficient breeding places in the felled trees 

 and stumps to prevent attacks on living timber. 



Whenever it is necessary or desirable to destroy the broods of 

 this insect in the logs, stumps, and tops, the timber sales or timber- 

 cutting regulations relating to living timber should require that if 

 the slash from winter, spring, and summer cutting is to be burned it 

 should be done during the succeeding fall, winter or spring, and that 

 the work be completed before the first of the succeeding July. Sum- 

 mer burning, to destroy the broods of this species, is undesirable and 

 entirely unnecessary if it can be done later. 



The regulations relating to infested timber should require that the 

 first work be directed either to removing the infested bark from the 

 main trunks of the standing trees or to felling and barking the trees, 

 or to utilizing the timber and burning the slabs, so that this essential 

 part of the work may be completed within the specified time, after 

 which the logging operations, including the disposal of the barked 

 and old dead timber, or of the living timber, if the last is included 

 in the sale, may be prosecuted until it is time to begin the barking 

 operations the following October, on any new infestation which may 

 appear within the area covered by the sales. 



The lodgepole pine, with its very thin bark, offers more favorable 

 conditions for combating this enemy than the thick-barked western 

 yellow pine and sugar pine. While the parent adults may attack 

 the thinner bark on the upper portion of the trunk and on smaller 

 trees, it is only in the thicker bark on the lower portion of the trunk 

 of the medium to larger trees that the broods will reach their best 

 development. Therefore, while many trees may be killed by the 

 beetles, the removal of the infested bark from the lower portion 

 of the trunks of a comparatively few of them may be all that is nec- 

 essary, and since this bark can be removed from the standing timber 

 the work need not be expensive. In fact, it may be desirable and 

 more practical to give the infested trees to anyone who will bark 

 them within the specified time. 



Whenever the infested timber is in the vicinity of streams or lakes 

 the insects may be destroyed by placing the unbarked logs in the 



