87 



on 21/1, after a long period of thaw, they were half free from ice. Then I again 

 captured some few larvae, two of them were held in aquarium, but died during the 

 winter. In the last days of January the ponds were ice-covered again and did not 

 thaw before 5/iv 1919; a t this date, when the pond was still ice-covered, I got 

 eleven larvae under the ice on one of the borders; they were all fullgrown and in 

 the following days (till 16/iv) on three excursions I caught all in all about twenty larvae. 

 On a journey to Suserup I got very many larvae in the same pond in which 

 C. lutescens was hatched, undoubtedly belonging to the same species. Further, on 



Textfig. 9. Pond in Store Dyrehave. O. cantans, ruslicus, C. morsitans. 



excursions to a little forest near Suserup, Arnehave, I found a pond which was al- 

 most exclusively inhabited by this larva; here it was present in thousands of spe- 

 cimens. All these finds were made in the time from 17/iv to 2l/iv. In the time from 

 Vv to 3/v there were no changes to note, but on 3/v I saw the first pupae, and 

 before 15/v all were hatched. On 6/y the first imago appeared in my cages; on 12/v 

 the last. By 21/y the ponds near Hillerod \vere both dry, by 7 /vi all those at Suse- 

 rup; however, in the ponds where 0. lutescens was hatched, and which were now 

 covered with grass, I found numerous specimens deep down in the grass. After July 

 the first I have never seen a single specimen, neither at Hillerod nor at Suserup. 

 Probably we have to do with a rather rare and early flying species. Its life-history 

 may be summed up as follows: The imagines are hatched in May and may prob- 

 lyba lay their eggs on the dried bottom of forest ponds, rarely in ponds in meadows, 



