65 



Note on the Occurrence of Larval Water-mites on 

 VARIOUS Aquatic Animals. 



By Chas. D. Soar, F.R.M.S. 



In a paper on Hydrachnidae, read on November 20tli, 1896, 

 (Journ. Q.M.C., Vol. VI., p. 318), I mentioned that I wished to 

 make myself familiar, as far as possible, with the larval forms of 

 Water-mites, and by a systematic search amongst all kinds of 

 pond-life to find out upon what creatures these larvae occurred, 

 and if the same species was always parasitic on the same host. 

 Since then I have collected and examined a great many aquatic 

 insects, etc., but the results so far have been rather poor. They 

 have, however, been considered sufficiently interesting to put on 

 record. 



i -T^fV 



One of the most common aquatic insects upon w^hich to find the 

 larvae of Hydrachnidae is Corixa geoffroyi. I have found a great 

 number of these, and some of them I have succeeded in keeping 

 alive long enough to allow the red globular water-mite larvae to 

 drop off and become free-swimming. The latter always turned 

 out to be nymphs of one of the species of the genus Hydrachna. 



In September 1898, on the Norfolk Broads, I took a number 

 of water-boatmen, Notonecta glauca, affiicted with the red globular 

 parasites. I brought some of these home, but, although I kept 

 one or two alive for a long while, I did not succeed in getting any 

 of the larvae to arrive at the next stage. In the spring of 1899 

 I again paid a visit to the same neighbourhood, and succeeded in 



Journ. Q. M. C, Series II. — No. 48. 5 



