378 Wa trter N. Hess 
Since this insect requires two years to complete its life cycle, the first 
winter is spent in the larval stage. From the time of hatching until 
late summer, the larva feeds freely in the cambium, but toward fall it 
“—* Brym 
constructs about itself a defensive wall of frass. In this condition it — 
spends the winter. During the second summer the larvae usually keep 
themselves protected by such a defense, moving about only as they need 
a fresh supply of food. Unlike most larvae, they do not feed in definite 
channels, but move about irregularly, excavating a blotch-like mine 
which is often rather extensive. 
Toward fall (about September) of the second year the larvae transform 
to pupae. About three weeks later they transform to adults. In this 
condition the insects pass the second winter. Toward spring the adults 
gradually gnaw their way through the bark, and emerge about the first of 
May. Though they feed very little before emerging, they eat a part of 
the bark as they bore their way to the exterior. They now no longer feed 
on the pine, but become pollen feeders like many other cerambycids. 
After emerging they soon copulate, and about the middle of May begin 
oviposition. 
ECONOMIC IMPORTANCE 
Rhagium lineatum, in the strict sense, can hardly be considered as an 
insect of economic importance in so far as any damage to living pines is 
concerned. hough its attack is limited to the region of the inner bark 
and the outer sapwood, it no doubt causes considerable damage to 
recently dead timber. Its excavations are usually extensive, and as a 
result the bark is frequently loosened, allowing moisture to enter. When 
water has once gained access, it is held by the large masses of frass. This 
is favorable for fungous growth, and hence the decay .of the tree is 
hastened. 
During the second and third years after the trees die, the exit holes made 
by the emerging adults admit large quantities of water, other insects, 
and fungi, by means of which the log is soon rendered useless for commercial 
purposes. 
Natural control 
In the control of the ribbed pine-borer, as in that of many other injurious 
species, nature has provided enemies which, under favorable conditions, 
are very effective in reducing their numbers. A wet season not only 
