4«5 
2.  i  he  shallow  grass-gTown  Ditches  along  the  sides  of  the  country 
roads,  and  the  earthen  gutters  at  the  sides  of  streets  in  the  towns 
are  also  breeding  places.  Where  the  surface  drains  in  the  towns  are 
cemented,  Anopheline  larvae  are  not  to  be  found. 
3.  Then,  scattered  about  the  country,  there  are  a  number  of 
larger  Ponds  which  are  formed  by  surface  drainage,  and  are  chiefly 
used  for  watering  cattle,  and  in  certain  localities,  where  water  is 
scarce,  as  the  water  supply  of  a  village.  The  margins  of  these  are 
invariably  grass-grown  and  full  of  Anopheline  larvae.  In  Great 
Pedro  Bay,  where  malaria  is  rife,  these  are  the  only  sources  of  the 
Anophelines. 
4.  Larvae  may  also  be  found  in  the  occasional  Pools  formed  in 
depressions  by  rain,  and  I  have  even  found  them  in  the  old  hoof- 
marks  of  cattle  when  left  undisturbed  for  some  time. 
5.  Anopheline  larvae  are  bred  occasionally  in  W ells,  especially  if 
not  very  deep,  and  I  have  found  them,  but  very  rarely,  in  barrels  and 
tanks  used  for  the  storage  of  water,  but  the  latter  are  a  fertile  source 
of  the  yellow  fever  mosquito,  the  Stegomyia. 
These  may  be  taken  to  be  the  principal  natural  haunts  of  the 
Anopheline  larvae,  but  there  are  other  breeding  grounds  which  are- 
artificial  and  are  the  direct  results  of  the  methods  of  agriculture  in 
the  Island 
6.  In  the  banana  plantations  in  the  northern  part  of  the  Island, 
where,  I  am  informed,  the  soil  is  very  heavy,  deep  drainage  is 
required  for  successful  cultivation.  Consequently  trenching  has  to 
be  extensively  carried  out,  and  along  these  Trenches  a  small  trickle  of 
water  is  generally  to  be  found.  Now,  it  was  very  interesting  to  me 
to  observe  that,  wherever  I  found  trenches  clean  and  free  from  weeds, 
with  a  smooth  bottom  and  an  even  gradient  so  that  no  pools  could 
form,  no  Anopheline  larvae  were  to  be  detected ;  but  as  certainly  as  I 
found  a  grass-grown  trench  with  pools  of  water,  so  surely  could  larvae 
be  discovered.  And  a  well-known  planter  remarked  to  me  that  clean 
trenches  meant  good  cultivation,  so  that  what  is  good  for  the  bananas 
is  bad  for  the  Anophelines. 
7.  In  the  southern  and  western  parts  of  the  Island,  where  the 
rainfall  is  much  less,  different  conditions  obtain.  Here  both  in  banana 
plantations  and  on  some  sugar  estates,  instead  of  drainage,  irrigation 
HH 
