122 



Marvels of Insect Life. 



the type changed to suit a more shiggish mode of hfe. In the examples we have 

 given of these parasitical beetles we see this evolutionary progression being repeated 

 in each individual, as though it were an object-lesson retained by nature to let us see 

 just how the change from one type to another may have been effected in the branching 

 off of families from the primitive beetle stock. In the majority of beetle-larvse the 

 triungulin stage appears to have been suppressed, unless the equivalent of it is passed 

 through before the egg hatches. 



The Snake-Fly. 



The snake-fly ^ gets its name from its remarkable appearance, due 

 to the elongation forwards of the fore-body and of the head behind, which gives 

 a miniature resemblance to the fore-part of a snake. The four wings are much like 

 those of the alder-fly, and the Insects are much about the same size — that is, one 

 inch across the expanded wings. The female snake-fly has a long, slender 



egg-placer of similar length 

 to the hind-bodv. What 



the object of the long neck 

 is, does not appear to 

 have been satisfactorily 

 explained, though it is 

 tolerably certain that there 

 is some reason for it, which 

 will be shown when more 

 attention to its life-history 

 has been paid bv observers. 

 The eggs, which are 

 laid in batches in the 

 crevices of decaying wood, 

 are long cvlinders with a 

 small knob at the upper 

 end. \W' give a photo- 

 graph of those of the spotted-necked snake-fly,- enlarged. 



The larva is chiefly noticeable by reason of its big head and the large size of the 

 first segment of the fore-body. There are no appendages to the hind-body, as in 

 the alder-fly larva, for the good reason that the snake larva is not an aquatic, but lives 

 in decaying wood, where it preys upon the numerous Insects there to be found. 

 When it has made the mistake of attacking an Insect larger or more capable of 

 offence than itself, it has a curious habit of wriggling out of the way, backwards, 

 rather than turning tail. By this method it has the advantage of retreating with 

 its face to the foe. It is a very voracious creature, but like many others of that 

 character it can upon occasion fast for long periods. Larva.' that have been kept 

 in confinement for observation purposes, and then possibly forgotten, have survived 

 without food for nine months. Such unfortunate individuals lose bulk, of course, 

 but appear to have the power to make up for lost time when they get the oppor- 

 tunity. It changes into a chrysalis without forming any cell or cocoon. In this 



1 Raphidia notata 2 R inaculic:ollis. 



Wasp-nest Beetle. 



The female beetle lays her eggs near the entrance to an underground wasp's-nest, and the 

 young grubs make their way to the interior and climb into the nest. Here they attack the 

 nearly full-grown grubs of the wasps and consume them as food. The two sexes are shown 

 enlarged to three times the natural size. 



