The  Anopheline  Adosquito  breeds  in  shallow  still  water  or  sluggish 
slowly-flowing  streams,  and  especially  where  it  is  weed  or  grass- 
grown  or  contains  green  algae  at  the  bottom.  This  is  very  important 
to  remember.  .Thus  the  larvae  will  be  found  in  shallow  ditches, 
grass-grown  edges  of  ponds,  the  shallow  margins  of  streams,  badly 
kept  irrigation  canals,  and  so  on.  It  is  rarely  found  in  deep  water 
clear  of  weeds.  On  the  other  hand,  the  Stegomyia  or  Yellow  Fever 
mosquito  breeds  in  old  vessels,  broken  bottles,  barrels,  and,  in  fact, 
in  anything  which  will  hold  water. 
The  local  conditions  in  Jamaica  under  which  I  have  found  the 
larvae  of  the  Anopheline  mosquito  may  be  classified  as  follows .-  — 
I.  Along  the  course  and  at  the  mouths  of  Rivers.  As  already 
mentioned,  these  spread  out  at  their  entrance  into  the  sea  so  as  to 
form  swamps  and  shallow  pools,  all  of  which  are  more  or  less  grass 
and  weed-grown.  This  is  well  seen  at  Annotto  Bay,  where  there  are 
no  less  than  three  large  swamps,  formed  by  the  two  rivers  which 
enter  the  sea  at  that  place,  and  one  of  these,  situated  right  in  the 
centre  of  the  town,  of  which  a  photograph  will  be  found  in  the 
appendix,  is  a  typical  Anopheline  breeding  pool.  Some  of  these 
swamps  and  pools  are  almost  on  the  same  level  as  the  sea,  and  are 
formed  by  the  sea  banking  up  the  sand,  and  thus  preventing  the 
outflow  of  the  water.  These  conditions  will  be  found  the  most 
difficult  to  deal  with  and  improve.  It  is  interesting  to  note  that 
mangrove  swamps  do  not  breed  Anophelines,  and  I  once  found  a 
curious  condition  along  a  road — at  one  side  a  mangrove  swamp  free 
from  Anophelines,  and  at  the  other  side  a  grass-grown  swamp  with 
numerous  larvae.  Larvae  will  breed  in  slightly  brackish  water,  but 
very  rarely  in  water  that  is  tidal  or  contains  more  than  a  certain 
proportion  of  salt. 
In  the  valleys,  along  the  courses  of  the  rivers,  where  they  spread 
out,  and  the  stream  becomes  shallow  and  sluggish,  similar  conditions 
may  be  found,  but  wherever  the  course  of  the  stream  is  rapid  and 
deep,  Anophelines  are  not  to  be  discovered. 
Occasionally,  after  floods,  the  depressions  in  the  surrounding  flat 
country  become  filled  up  with  water  and  form  suitable  breeding  places 
for  mosquitoes.  These  are  not  important  unless  in  the  immediate 
vicinity  of  towns  and  villages. 
