344 NATURAL HISTORY OF AQUATIC INSECTS CH. 



them. At this time the fly carefully avoids spreading 

 her wings, for though they afterwards become firm as 

 sheets of talc, they are at present soft as wet paper. 

 It is important to avoid the slightest derangement, 

 or even contact with one another. The abdomen is 

 carefully bent into such a position as to avoid touch- 

 ing them. As the wings expand, we can see the 

 veins spreading further and further apart and the 

 folds becoming effaced. The expansion is apparently 

 due to the injection of liquid into the veins. When 

 I took a fly which had perished during extrication, I 

 found that the wings were soft, and could be expanded 

 by the fingers ; but as soon as they were released, 

 they returned to their original folded condition. 

 The expansion of the wings is usually completed in 

 less than a quarter of an hour, but when first expanded 

 they are not yet firm or dry enough for flight. More 

 than two hours are often necessary before the wino-s 

 can be spread out horizontally, and two or three 

 hours more are required before they are able to 

 support the weight of the body. All the time that 

 the wings are expanding, the abdomen is being 

 gradually prolonged. When the Dragon-fly first 

 emerges, its colours arc faint, but they gradually 

 increase in distinctness and brilliancy." 



The process of egg-laying has its difficulties, for, 

 while the female Dragon-fly is apparently ill-fitted to 

 enter water, the larvae which escape from the eggs 

 cannot endure more than a short exposure to air. 

 The plan pursued seems to vary in the different 

 species. It is said that some Dragon-flies merely 

 drop the eggs, singly or in groups, into the water. 



