TKEE MOSQUITOS 97 



Algeria, necessitating careful drainage, has diminished 

 malaria. 



Botanic gardens are \'ery frequently the preserves of 

 the mosquito, for on them ornamental ponds and fountains 

 and innumerable tubs and water-barrels are the rule, 

 and unless these are stocked with small fish they are a 

 fertile source of mosquitos. As previously pointed out, 

 trees and plants may aid to an enormous degree in the 

 production of mosquitos. Tree mosquitos have been 

 conveniently grouped by Dr. Urich in Trinidad into 

 the " rot hole," " bamboo," and " wild pine " groups. 

 Old trees are often honeycombed with decay holes, and 

 in these water collects and mosquitos lay their eggs. 

 When bamboo cane is cut down it is very common 

 for the workmen to leave an internode, in which one 

 or more pints of water can collect and act precisely 

 as a miniature pond. I have already referred to the 

 " wild pine " [Bromeliacew) which infest trees in enor- 

 mous numbers, and in the aggregate hold up a great 

 quantity of water. There are in addition numerous 

 other small water-holding plants, such as the Aroideie, 

 which in towns, if allowed to grow up in neglected 

 places, give rise to a mosquito nuisance in a very short 

 time. Therefore more attention should be given to 

 the question of the care of bush and plants in tropical 

 towns than is usually done at the present time. Bush 

 should be rigorously cut down around towns, and on 

 no account should it be allowed to increase in yards 

 ^nd gardens as is almost invariably the case. Not only 

 does bush hold up water, but it also gives excellent 

 ' cover to mosquitos and enables them to progress from 



