STEGOMYIA SURVEY 155 



as the flea, bug, and cat. In a few instances I have 

 found them in drains in the houses, mixed with culex 

 larvae. In these cases tlie water w^as dirty. This latter 

 point recalls the statement often made that larvse purify 

 water, and that they are useful in tlie drinking-water 

 butts because they will remove pathogenic organisms 

 should any gain access. For this reason certain 

 municipal authorities have not been so active in their 

 destruction as they might otherwise have been. We 

 have no evidence whatever that tliey do remove 

 pathogenic germs ; their natural food is green algai 

 and diatoms. But from the practical point of view, 

 we know the danger of stegomyia larvae and how surely 

 yellow fever will spread wherever these larv£E are, that 

 it is hardly practical to keep these larva? for any sup- 

 posed good they may do when we know the positive 

 disaster they bring about. 



Stegomyia Surveij. — In every town I have visited 

 for the purpose of strengthening or drawing up 

 measures against fellow fever, it has been my invariable 

 rule to visit either all the houses or to take repre- 

 sentati\'e blocks, and go through each house, garden, 

 and yard systematically. In these tours I am accom- 

 panied by the sanitary inspectors and one or more 

 medical officers. We are armed with white enamelled 

 iron spoons, with Mdiich we can rapidly take a sample 

 of water and see if larvae are present. I examined 

 all water, drinking and w^ashing, inside or outside the 

 house, and whether contained in cisterns, barrels, 

 buckets, tubs, tins, goblets, vases, " monkeys," " destil- 

 ladores," wells, antiformicas, broken bottles, etc. If 



