2l6 



INSECT LIFE. 



If the bark be pulled from dead branches or trunks 

 of trees, the inner layer and the sap-wood will be 

 found to be ornamented in many cases with burrows 

 of more or less regular form. These smoothly cut 

 figures are the mines of the engraver-beetles. Many 

 kinds of these engravings can be found, each charac- 



FiG. 183. 



teristic of a particular kind of engraver-beetle. A 

 common pattern is shown in Fig. 183. The beetles 

 that do this work are mostly of cylindrical form and 



of small size ; many spe- 

 cies are almost micro- 

 scopic, and the larger 

 ones rarely exceed a 

 quarter of an inch in 

 length. They are usu- 

 ally brown, sometimes 

 black, and with many 

 the hind end of the body 

 is very blunt, as if cut 

 off. These beetles be- 

 long to the family SCOLYTID^ (Sco-lyt'i-das). 



The insects known as horn-tails are often found 



Fig. 184. — A horn-tail. 



