112 INSECT ARTIZANS AND THEIR WORK 



of long galleries. These are connected within bv 

 other galleries. Colobofsis lives in a similar manner, 

 and for the protection of the colony keeps a big- 

 headed worker on duty as a sentinel at the doorway. 

 The worker's head just fiUs the space, and its jaws 

 are ever ready to argue the matter with an unwel- 

 come caller. One who has the right of entry is 

 admitted by the worker withdrawing backwards. 



Among the beetles there are a number of accom- 

 plished carpenters, some of them spending several 

 years in the excavation of long burrows in trees, 

 others engaged for generations in what the house- 

 holder considers the more reprehensible business 

 of drilling into his most cherished articles of wooden 

 furniture and reducing them to fine dust. In the 

 days when our navy consisted of wooden ships, some 

 of these beetles were in permanent league with our 

 enemies in the effort to destroy these wooden walls. 

 It is not necessary to deal at length with these 

 carpenter beetles, for their methods are much the 

 same in many cases. A few examples must suffice. 



The smaller of the carpenter beetles content 

 themselves with tunnelling in the bark of trees, 

 and such attacks are frequently regarded as of little 

 moment to the tree, but they have been shown in 

 some cases to interfere with the normal flow of 

 the descending sap, and so produce an unhealthy 

 condition which renders the tree susceptible to the 

 attacks of more destructive species. Moreover, 

 damp finds its way into these borings, also the spores 

 of wood- destroying fungi which complete the work 



