230 NEW YORK STATE MUSEUM 



and remains stopped till the pools are refilled in late autumn, 

 and the stems and leaves, now dead, fall into the water. I have 

 gathered the eggs in the middle of July and again in the middle 

 of October and found them at apparently the same stage of de- 

 velopment. Eggs placed at the latter date in a. bowl of water 

 in my laboratory hatched within a week. I did not try hatching 

 any of them earlier. 



Exposed as they are above the water, these eggs are subject to 

 parasites, which destroy often a large proportion of them. 

 From a handful of bur reed leaves well studded with Lestes eggs, 



Fig-. 6 The egg- of Lestes uncati 



I once bred large numbers of the following parasites, the two 

 last named being hyperparasites on the third named in the list. 



Brachista pallida Ashm. 



Centrobia odonatae Ashm. 



Polynema needhami Ashm. 



Tetrastichus polynemae Ashm. 

 Hyperteles polynemae Ashm. 

 The nymphs live among submerged plant stems. Their ex- 

 tremely slender legs, long swaying bodies, and leaflike gill 

 plates, together with a sober color pattern of greens and browns, 

 render them very inconspicuous when in their native haunts. 

 In aquariums they are rather shy, and do not feed under observa- 

 tion so readily as do many other genera. I have observed them 

 eating some of the larger entomostraca and smaller dipterous 

 larvae (Corethra and Chironomus). 



Since the nine species occurring in or regional in New York 

 State have all been described several times in recent and avail- 

 able papers, and since the females are well nigh indistinguish- 

 able, and determinations must at present be based on the males 

 and chiefly on the form of the terminal abdominal appendages 

 of the males, I have not thought it worth while to give descrip- 



