334 ^^-^'^' VORK STATE MUSEUM 



di\(.;i-i;ing- somewhat sinuous larval L;allerit.-s which ruii a]:)proxiinat(_'ly trans- 

 versely of the wood fillers. This is the work of a large borer known 

 as T o m i c u s c a 1 1 i g r a p h u s Cierm., an insect that occurs in the 

 thicker bark of trunks and larger limljs of both hard and soft pines. 

 It normally does not cause very much injury bu.; under exceptional con- 

 ditions it ma_\- become so alnindant as to kill a tree very rapidly, so much so 

 that the writer has known )oung pines, in apparently excellent condition, 

 killed in lo weeks' time. These borers sometimes become so abundant 

 as to eat away |)ractically all of the inner bark, a condition represented at 

 plate 56, figure 3. 



Farther up t)n the tree in the thinner bark of the trunk and the medium 

 thick bark of the larger limbs, a smaller species may be found at work in 

 some pines and its method of operation is well shown in plate 60, figure 3, 

 which represents the longitudinal burrows and the lar\al galleries of this 

 smaller species, Tomicus cacographus Lee. This is a very badly 

 infested piece of bark and plate 60, figure 2, illustrates the work of this 

 insect on limbs of hard pine which it had entered in the fall of 1900. It 

 will be observetl that these galleries are very irregular and anastomose with 

 out a[)parent reason. These are evidently galleries which the beetles have 

 made for feeding purposes and in which the\' pass the winter. 



Higher up on a white pine in the still thinner liark of the smooth 

 trunk, a smaber form, th(; pine bark beetle, T o m i c u s p i n i Say, may be 

 observed at work. This s|jt'cies operates not onl\- in the trunk fnit also in 

 the medium thick bark of the smaller limljs and not infrecpienth' attacks liv- 

 ing tissues. Plate 59, figure i, which is from a photograph taken with a 

 light background, represents the numerous exit holes which this species 

 may make in a badly infested section of a trunk and also a number of small 

 jjitch tubes and plate 59, figure 2, shows the inside of the same piece of 

 bark photographeil in a similar manner. The method of operation of this 

 species is well illustrated, the central chambers, the primary galleries and 

 the (iiiatmg mines ot the young together with larger fiat tortuous mines 

 of another species known as the pine sawyer, ]M o n o h a m m u s con- 



