304 Marvels of Insect Life. 



Photo by] [E.Step.F.L.S. 



Dragon-Fly Nymphs. 

 Nymphs of one of the large cylindrical-bodied species. That to the left has its mask retracted; the one to the right has it partially 

 extended, showing the two-jointed portions which fold up under the head. The valves at the end of the body are shown also. 



is withdrawn, and it clings to the empty old skin whilst its wings, so long cramped 

 up in the little hard pads on its back, hang limp but visibly expanding. 



When man, after many experiments, acquired the means of flying he had to make 

 many trials, a large proportion ending fatally for the intrepid experimenter. But 

 the dragon-fly, after waiting a little to allow his wings and integuments to harden, 

 knows exactly how to use them, and spreading them, starts swiftly on a level course, 

 wheeling sharply to right or left, and backing with facility. In the pond he preyed 

 upon the other inhabitants, and now in the air he pursues the same methods of 

 subsistence, but upon the winged Insects. 



In addition to the stout-bodied, cylindrical, and the broad-bodied, flat species 

 of large size, there are others, the demoiselles, with very slender bodies and delicate 

 narrow wings, the bodies striped with blue and black ; but the general facts of their 

 life-history are all much alike. 



Spinners of Silk. 



From very early times man has been acquainted with, and has made use of, 

 the silk-producing powers of Insects. The silkworm ^ that originally came from 

 China or India, has been the principal source of the finest raiment with which the 

 human species has clothed itself, but the facultv of producing silk is shared by many 

 Insects in a minor degree. In most of them it is utilized in the final stage of the 

 grub state to make provision for the security of the chrysalis, but many caterpillars 

 possess it already when newly issued from the egg. As an example of this we may 

 cite the case of the young caterpillar of the puss-moth,'^ which feeds upon the upper 

 surface of the leaves of sallow, willow, and poplar. The latter are not only glossy, 

 affording an insecure foothold, but are kept in a state of constant fiuttering by the 

 slightest movements of the air. The tiny caterpillars, looking like smuts that have 

 clung to the leaf and that might be detached by a breath, at once set to work to spin 

 a little pad of silk on the leaf, in which the hooks of their feet may catch, and so 

 enable the animated particle to feed in safety no matter how violent the jerking 

 of the leaf from side to side. 



1 Bombyx mori. ^ Dicranura vinula. 



