INSECTS. 



173 



of this table, which noise was heard for a year or two, when a long-horned 

 beetle made its exit therefrom. Subsequently the same noise was heard 

 again, and another insect, and afterwards a third, all of the same kind, 

 issued from this table-leaf, — the first one coming out twenty, and the Lasl 

 one twenty-eight years after the tree was cut down." How long before 

 the tree was cut down the eggs were deposited we have no means of 



knowing. 



Bristle-Tails and Spring-Tails. 



In damp earth and under decaying boards, the naturalist frequently 

 finds some minute forms, which are to him very interesting, since they are 

 the lowest of the whole insect series. Unlike their relatives, they have no 

 wings, and have to depend on their rapid locomotion, or upon the spring 

 with which many are furnished, to escape from danger. This latter is a 

 curious forked appendage, folded on the under surface of the abdomen, 

 and capable of being suddenly straightened out, send- 

 ing the insect several times its own length. Our cut 

 does not show this spring, but it illustrates the pecu- 

 liar appearance which one of the common species of 

 the northern states presents when he is magnified. 

 Although so small, these little forms are brightly 

 colored ; this species being yellow, shading off into 

 brown or even purple, while others may be of almost 

 any hue of the rainbow, or even all the colors may 

 be present on the one specimen at the same time. 



We have given the explanation of the common 

 name spring-tails, applied to some of these forms, in 



the last paragraph ; the other 

 term refers to the fact that in 

 others of the group the abdo- 

 men terminates with two long 

 bristles. The most familiar example of this is the 

 ' silver-fish,' a little silky, gray form that is occasion- 

 ally seen around books and papers. It does son if 

 damage to these as well as to carpets, clothing, and 

 silken goods by gnawing holes in them, yet in this 

 respect it is far exceeded by many other insects. 



There is one of the spring-tails which is well 

 known to the microscopists. This is the Podura, 

 a little dark-colored form whose body is covered with minute scales. These 

 scales have a very peculiar appearance under the microscope, and they are 



Fig. 156. —A spring-tail (En- 

 tomobrya). 



Fig. 157. — Podura. 



