DRAGON-FLIES 41 



The Odonata fall into two well-marked groups, or 

 sections. In the first of these l the hind-wings are 

 usually broader than the fore-wings at the base, 

 while both pairs of wings are retained in an ex- 

 tended position when the insect is at rest. More- 

 over, the compound eyes meet on the top of the head, 

 except in the case of a somewhat rare species called 

 Gomphus vtilgatissimus. This section includes the large, 

 rapidly flying dragon-flies to which the name " horse- 

 stingers " is often applied though, of course, they have 

 no stings, nor are they connected in any way with 

 horses. Some of the species fly to great distances, far 

 from water, and are even known to migrate in swarms. 

 Two well-known examples from this section are 

 Libellula depvessa, in which the abdomen is broad and 

 much flattened, with a bright blue bloom in the case 

 of the male ; and ^Eschna cyanea, whose abdomen is 

 very long in proportion to the rest of the body, and 

 cylindrical in contour. The latter is one of several 

 species which display numerous yellow, green, or blue 

 spots, symmetrically arranged on a dark ground 

 colour. 



In the second section 2 all the wings are alike 

 in shape, both pairs being equally narrow at the 

 bases. When the insect is at rest, they are held 

 more or less completely closed over the back. 

 Further, the compound eyes, though large and pro- 

 minent, do not meet on the top of the head. The 

 dragon-flies of this section are more frailly built than 

 their Anisopterid allies, and are much slower in flight. 

 Some of the exotic forms rank among the most 

 brilliantly coloured insects known, while several of 

 our own species are very beautiful. The so-called 

 1 Called Anisoptera. 2 Called Lygoptera. 



