416 JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, Vol. XX. 



upon larvae of anopheles, which float on the surface. Occasionally 

 it may be seen to turn its body in a half circle, when any moving 

 object conies near it, evidently keeping a sharp look-out for the 

 approach of its prey. It is exceedingly voracious and when hungry 

 will seize any larva that ventures without striking distance, 

 the movements of its head and neck being so rapid -that the eye 

 cannot follow them. Small larvae are swallowed whole, disappear- 

 ing instantaneously ; large larva) are seized and held remorselessly 

 in spite of their struggles, and are rapidly devoured while still alive. 



In Bombay and possibly in other places Cidex concolor plays a 

 definite role in reducing the number of anophelines and is possibly 

 one of the factors which assist in producing fluctuations in malaria 

 from year to year. A number of aquatic insects and aquatic larvae 

 are known to prey upon mosquito larvae. Among these may be 

 mentioned dragon-fly larvae, ephemera larvae, the larvae of chironomus 

 and corethra, water boatmen and certain among the water-beetles. 

 All these may be found breeding in Bombay in pools and tanks and 

 wells. In addition I have recently discovered a minute almost 

 microscopic water-bug which attacks and kills large numbers of 

 anopheles larvae. This little bug, which is only about l-40th of 

 an inch long, is present in considerable numbers in some of the 

 wells in the north of the island. It is black in colour and runs 

 readily about on the top of the water. It possesses a long suctorial 

 proboscis tucked away on the undei'side of its body. Quite recently 

 I was breeding out a number of anopheles mosquitoes from larvae and 

 was rather disappointed to find that all the larvae were dying. On 

 careful examination of the jar in which they had been placed I 

 noticed two or three minute black bugs running rapidly about on 

 the surface of the water. Out of curiosity I placed one in a small 

 tube with some anopheles larvae and very soon I saw the bug gently 

 approach the larva at its tail end and then gradually move forward 

 to the thorax. The larva did not appear to notice anything but 

 by watching carefully with a magnifying glass it could be seen 

 that the bug had inserted its proboscis into the thorax of the larva 

 and was busy sucking out its juices. I placed one small bug in a 

 bottle with a dozen anopheles larvae and in twenty-four hours all 

 but two were dead. 





