312 THE RIVER-SIDE NATURALIST. 



3 and 4. Libellula puella and Libellula cceruleus. The 

 Libellula puella has the body of a greenish-blue ; wings of 

 equal length, with a cloudy, brown spot in the middle. 

 The length of the insect is about two inches. It is often 

 to be seen sporting on the waters in May and June. There 

 is a variety with the body red, with yellow and black lines ; 

 the wings clear, with marginal spots. 



The dragon-flies are very remarkable for the rapidity 

 and power of motion. Kirby, on " Motion of Insects," 

 says : " Their four wings, which are nearly equal in size, 

 are a complete and beautiful piece of network, resem- 

 bling the finest lace, the meshes of which are usually 

 filled by a pure, transparent, glassy membrane. In two of 



THE LIBELLULA PUELLA. 



the genera belonging to this tribe the wings, when the 

 animal is at rest, are always expanded, so that they can 

 take flight in an instant, no previous unfolding of these 

 organs being necessary. In Agrion, the other genus of 

 the tribe, the wings when they repose are not expanded. 

 I have observed of these insects that, without turning, they 

 can fly in all directions backwards, and to the right and 

 left, as well as forwards. This ability to fly all ways 

 without having to turn must be very useful to them when 

 pursued by birds. Leeuwenhoek once saw a swallow 

 chasing an insect of this tribe in a menagerie about one 



