DRAGON-FLIES 171 



the peculiar fore legs and by a pair of claspers which project 

 from the last segment but one of the abdomen. The fly of 

 Ephemera vulgata is 16-18 mm. long (body only), and has 

 three long tail-filaments. The wings are opaque, brownish, 

 spotted and intersected by very numerous veins, the abdomen 

 spotted and streaked with dark colour. 



There is much diversity in the mode of egg-laying. Some 

 Ephemerids discharge all their eggs at once into the water, 

 sometimes resting during the operation on the surface with 

 their long tail-filaments outspread. Such species are short- 

 lived in the winged state. Or the eggs may be laid at the 

 surface of the water, a few at a time, but at frequent intervals. 

 Certain others (Baetis), which as larvae are distinguished by 

 their unusual swimming powers, enter the water, and lay their 

 eggs carefully among the stones. The female folds her wings 

 until they resemble sticks protruding from the thorax, and 

 descends into the stream, overspread by a film of air, so that 

 her body is not wetted. After emerging she enters again at 

 another place, and lays a few more eggs. Many Ephemerids 

 fall victims to fishes at the time of egg-laying. 



35. DEAGON-FLIES (Odonata) 



It is needless to say that the early stages of a dragon-fly are 

 passed in the pools over which the winged flies afterwards 

 hover. Few aquatic insects are more familiar than this larva. 

 Unlike the flies, which are often, though not always, gay- 

 coloured, the larvje are of a dull brown or green, resembling, 

 the clayey bottom or the dusky vegetation on which they live. 

 The body may be plump or slender according to the shape of 

 the adult, but is nearly always thicker and shorter than it after- 

 wards becomes. The head is distinct and usually very large. 

 It bears slender antennae and (in most cases) very large eyes, 

 which we may suppose to be adapted rather to future than to 

 present needs; they sometimes undergo a notable develop- 

 ment during the larval stage. The jaws are suited to the 

 wants of a fiercely carnivorous creature. The mandibles and 

 maxillae are long and toothed at the end; the labium very 

 long and jointed near the middle, so that it can either be 

 folded up, when the broad extremity covers the mouth, or 



