THE INSECTS. 213 



hundred feet long ; the little insect flew with such astonish- 

 ing rapidity to the right, to the left, and in all directions, 

 that this bird of rapid wing and ready evolution was unable 

 to overtake and entrap it, the insect eluding every attempt, 

 and being generally six feet before it; The species of the 

 genus Agrton cut the air with less velocity ; but so rapid 

 is the motion of their wings that they become quite in- 

 visible." 



Dragon-flies are most abundant near water, as they 

 deposit their eggs in that element, the larvae and pupae 

 being entirely aquatic. They are great devourers of all 

 other aquatic insects. 



That the larvae of dragon-flies are very deleterious to the 

 fry of fish the following will testify : 



" In the Hungarian Rovotani Lapok of December last, L. 

 Bizo states that the larvae of some of the Libellulce, species 

 not determined, have made such ravages in the piscicultural 

 establishment of Count Palffy at Izomolany, that in a pond 

 in which 50,000 young fish were placed in the spring of 

 1884 only fifty-four could be found the following September ; 

 but there was a large quantity of the Libellulce referred to " 

 (Zoologist, April 1885). 



The metamorphosis from the pupa to the imago is 

 extremely interesting. When the final transformation is 

 about to take place, the pupa crawls out of the water on 

 the nearest object to it, either a rush or stem of a plant or 

 a stick, fixes itself by its legs, which are furnished with 

 hooks, and the skin then splitting up the back, the imago 

 or perfect insect is released. The body and wings, which 

 are still folded up, are, however, quite soft and moist. 

 The wings become rapidly developed, and it dries both its 

 body and wings in the sun, and soon takes its departure, 

 roaming in all directions. 



Sometimes these insects appear in enormous quantities. 

 Kirby mentions that Meinechen once saw, on a clear day, 

 such a cloud of dragon-flies as almost to conceal the sun. 

 At times, in Germany, cloud-like swarms of the L. depressa 

 were seen at Weimar and other places extending over a 

 very large district. 



