98 CULTIVATION AND THE MOSQUITO QUESTION 



point to point Bush also is one of the chief agents 

 in keeping out fresh air in towns, where fresh air is 

 above all things necessary ; it also forms cover for 

 plague rats and their fleas. By some it is argued that 

 bush helps evaporation. The contrary is the case ; the 

 admission of more air and light would accomplish far 

 more. Plant cultivation in towns also leads to various 

 devices for keeping them moist or protected from 

 ants, and these devices in their turn lead to the breed- 

 ing of mosquitos. Thus, flower-pot saucers are a very 

 common breeding place of the stegomyia, and so are 

 the antiformicas with which rare plants are protected 

 from the inroads of the umbrella ants. I have found 

 larvae in them in very numerous instances. And whilst 

 on the subject I would like to draw attention to the 

 very numerous occasions upon which I have found 

 mosquito larva?, usually those of stegomyia, in glass 

 vases used either for holding cut flowers or, more 

 frequently, for propagating cuttings of the Croton plant ; 

 the reason is, of course, that either the water is not 

 changed often enough, or when the water is changed, 

 the larvae and eggs cling to the roots when the old 

 water is thrown away, and when the fresh water is 

 added the larvae are as vigorous as ever. Upon one 

 occasion I found a swarm of stegomyia larvie breeding 

 in a pool that had formed between the buttresses 

 of an old silk-cotton tree. Another not very obvious 

 site for the fostering of mosquito larvae are the small 

 pools which are found amongst the rocks of a rock- 

 bound coast. These, in many instances, come close 

 u^) to human habitations, as in St. Vincent, and in 



