68 A BOOK OF INSECTS 



Order VII. — Ephemeroptera. 



This order includes the may-flies (Ephemeridce). In 

 the adults the mouth-parts are very imperfectly deve- 

 loped, or quite absent ; the hind-wings are much smaller 

 than those of the front pair ; while the antennae are ex- 

 tremely short and bristle-like. Two or three very long 

 tails, or cerci, are carried at the end of the abdomen. In 

 their early stages, the may-flies are aquatic. Metamor- 

 phosis is incomplete, but the nymphs do not resemble 

 their parents, being campodeiform, and perfectly adapted 

 for an aquatic existence. Their mouth-parts are mandi- 

 bulate, and they feed upon vegetable substances and 

 small animals. May-flies are found in all parts of the 

 world, upwards of three hundred species having been 

 described. The common British may - fly — the " grey 

 drake " of the angling fraternity — is Ephemera vulgata. 



Order VIII. — Odonata. 



The dragon flies, which are comprised in this order, 

 may be easily recognised by several well-marked char- 

 acters. The head is large, and can be moved freely, 

 owing to its slender attachment to the thorax. The 

 antennas are so small as to be scarcely noticeable, but 

 the compound eyes are very large, while there are three 

 simple eyes, or ocelli, on the brow. The mouth-parts 

 are formed for biting, the mandibles being exceptionally 

 large and powerful, while both pairs of maxillae are 

 flattened, and otherwise modified, so as to form — in con- 

 junction with the hinged upper lip or labrum — a kind 

 of trap for catching and holding the insects upon which 

 dragon-flies feed. The thorax of the dragon-fly is very 

 remarkable. When viewed from the side, its rings, or 



