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. Tins 
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 m the vicinity of streams or lakes 
the insects may be destroyed by placing the unbarked logs in the 
