LIFE HISTORIES OF THE ODONATA. 45 



make a little notch in the plant for their eggs. With 

 the exception of this last habit, all that has been nar- 

 rated has been verified by our personal observation. 



On the 12th of October five pairs of Diplax rubicun- 

 dula were all together in a little bay hardly two feet 

 square, which ran in from a reedy pool, depositing eggs 

 so earnestly that the observer was allowed to approach 

 very close. Two downward strokes of the abdomen 

 seemed to be necessary to deposit the eggs, which floated 

 for an instant, although some went at once to the bot- 

 tom. We are of the opinion, based on personal obser- 

 vation, that this habit of ovipositing very materially 

 aids the female in flight and thus enables her to elude 

 the everwatchful frogs which lie in wait at such times. 

 Many a hapless female and her carefully deposited clus- 

 ter of eggs disappear down the cavernous gullet of the 

 frog. 



It is evidently with the view of preventing this catas- 

 trophe that the female of a species of JEschna, as related 

 by Marchal,^^ has been observed to plaster its eggs with 

 sand or nuid at the margin of the pool. For the pur- 

 poses of study, the eggs of the Odonata are readily ob- 

 tained ; gentle pressure on the abdomen of an egg laden 

 female will furnish a few. 



Owing to the protracted development, we have been 

 unable to determine the exact length of time required for 

 the eggs to hatch. 



European entomologists give periods varying from six 

 days to several months, the latter being the case when the 

 winter is passed in this stage. A lot of Diplax rubicun- 

 dula eggs obtained early this fall are yet unhatched and will 

 probably pass the winter so. Packard"^ has described 



