2i 4 POPULAR SCIENCE MONTHLY 



the annual cycle of metamorphoses and emerges as a beetle of that 

 generation about a year after the egg is hatched. The burrows 

 are made by the strong horny jaws of the larvae, which shred every 

 particle of the wood in the course of the burrows, all of it passing 

 through the intestinal canal of the larvae. Only the scanty proto- 

 plasmic contents of the wood cells, however, are digested for nourish- 

 ment, and the dry refuse, resembling fine saw-dust, is packed behind 

 the larva as it progresses in its burrow. The burrows are compara- 

 tively large and when numerous, as usually they are, they cut across 

 the wood fiber so frequently that the trunk and larger branches are 

 often completely riddled by them. 



Such is the condition to which the wood of the black locust tree is 

 habitually reduced by those insects and to which it is the special ob- 

 ject of this article to call public attention. It is almost needless to 

 add that such burrows render the wood useless for timber, of little 

 value as fuel, and more subject to decay than is the uninjured wood. 

 Many and various kinds of insects burrow in the dead wood of different 

 kinds of lumber and fuel and thereby do much injury, but compara- 

 tively few species bore exclusively in living wood, and these are ex- 

 tremely injurious. The destructive borer of the locust tree and the 

 smaller but hardly less destructive borer of the mezquite tree, already 

 mentioned, are two of the best-known examples of the latter kind. Per- 

 haps the best-known example of the former kind is the hickory wood 

 borer, which householders often find in their fuel ; especially that which 

 has been felled in late winter or early spring. These borings in 

 hickory wood are closely like those which are made in the living locust 

 trees, and the locust and hickory borers are so nearly alike in appearance 

 in all three of their metamorphoses that it is difficult for the ordinary 

 observer to distinguish them apart. The hickory borer, however, bur- 

 rows only in recently felled dead hickory wood, its incubation therein be- 

 ginning in the spring ; while the locust borer burrows only in the living 

 wood, its incubation beginning in late summer and continuing until 

 frosts prevail. This last-mentioned fact is important with reference to 

 any remedies against the ravages of the locust borer that may be pro- 

 posed. Hickory wood which is felled in autumn or early winter is 

 likely to escape its borers by becoming too dry to serve their needs when 

 they reach the beetle stage in the spring ; but for the locust tree, after 

 its sapling stage, there is no immunity from its borers so long as it 

 lives. 



Apparently there are several reasons why the ravages of the locust 

 borer have largely escaped popular attention, such as the destruction of 

 fruit and foliage by insects receives. The bark of the tree usually re- 

 mains intact long after the wood beneath it is greatly injured. The 

 small pits and punctures which are made in it by the female beetle for 

 depositing her eggs are not ordinarily noticeable, and even the holes by 



