BREEDING-PLACES 99 



such cases the domestic mosquito, hke the stegomyia, 

 may breed in them. These pockets should be either 

 filled in with concrete or so chiselled that water can- 

 not remain in them. In many of the more low-lying 

 swampy coasts crab-holes occur in enormous numbers 

 in the sandy soil, and in them are bred vast numbers 

 of mosquitos. In fact they constitute the chief 

 nuisance in those houses which are situated near 

 the sea. 



