340 NATURAL HISTORY OF AQUATIC INSECTS CH. 



with Dewitz's experiments. Thus, Agrionid larvae 

 sway their abdomen from side to side, and ^Eschnid 

 larvae often come to the surface and take air directly 

 into the intestine. These expedients are most fre- 

 quently resorted to when the water is foul. 



The escape of the Dragon-fly from its larval skin 

 is described by Reaumur in his usual lively style, 

 and I think that the reader will like to have his 

 account as nearly unabridged as possible. 1 



" Most, perhaps all, of the larvae of Dragon-flies," 

 says "Reaumur, " must live ten or eleven months 

 beneath the surface of the water before they can 

 undergo transformation ; there may possibly be 

 Dragon-flies produced in autumn from eggs laid in 

 spring ; if so, the larvae, enjoying the season most 

 favourable to growth, develop faster than the rest. 

 [Such cases are not certainly known to occur, though 

 they are probable enough ; certain large Dragon-flies 

 are believed to live two and even three years as 

 larvae.] However this may be, from April to the end 

 of September, and even to the middle of October, 

 Dragon-flies emerge every clay. 



" The change which is to convert an aquatic Insect 

 into an inhabitant of the air takes place out of the 

 water. All the larvae, however, which one sees either 

 wholly or partially out of the water are not absolutely 

 ready to become winged. Often when they have 



1 The original is to be found in the eleventh memoir of 

 Reaumur's sixth volume. Here as elsewhere Reaumur is not 

 very careful to distinguish the various species described, but 

 many of his observations seem to have been made upon yEschna 

 cyanea, which is very common both in France and in England. 



