VII] ENEMIES 73 



mosquito larvae, its leaves closing quickly on any animal that 

 touches them. 



The larvae are sometimes destroyed by fungi and bacteria, 

 but these groups of organisms are neither of them very im- 

 portant enemies. 



Both the adult insect and its immature stages are para- 

 sitized by various species of Protozoa and also by nematodes 

 and trematodes. Insect enemies are responsible for the 

 destruction of enormous numbers of mosquitoes. The larvae 

 of Hydrophilidae and Dytiscidae devour large numbers of larvae, 



Fig. 32. Anopheles maculipennis <? captured in Cambridge, shewing acarine 

 parasites attached to the body. (From a photograph taken by Professor 

 Nuttall.) 



and one Dytiscus larva has been known to destroy 434 mos- 

 quito larvae in two days. Whirligig beetles (Gyrinidae) are 

 also great enemies of the larvae, and no Anopheles has a chance 

 in any water inhabited by them. Similarly the various species 

 of aquatic Hemiptera destroy the larvae and also emerging 

 imagoes, or females laying their eggs. Dragon-flies in the 

 adult stage feed on other flying insects, and in their immature 

 stages devour mosquito larvae, etc. Their voracious habits, in 

 all stages, are notorious, and they must destroy enormous num- 

 bers of Culicidae along with other Dipt era. Some of the most 

 formidable natural enemies of the mosquito larvae are to be 



