﻿CERTAIN 
  NURSERIES 
  OF 
  INSECT 
  LIFE 
  IN 
  WEST 
  AFRICA. 
  293 
  

  

  rot-hole 
  in 
  a 
  particular 
  silk-cotton 
  tree 
  (Eriodendron 
  anfractuosum) 
  at 
  Nsawam 
  the 
  

   following 
  mosquitos 
  and 
  Ceratopogonine 
  midges 
  were 
  reared 
  : 
  — 
  

  

  Mosquitos. 
  Ceratopogonine 
  Midges. 
  

  

  Culex 
  (Culiciomyia) 
  nebulosits, 
  Theo. 
  Culicoides 
  accraensis, 
  C. 
  I. 
  & 
  M. 
  

  

  Aedes 
  (S.) 
  apicoargenteus, 
  Theo. 
  C. 
  clarkei, 
  C. 
  I. 
  & 
  M. 
  

  

  A. 
  (S.) 
  dendrophilus, 
  Edw. 
  C. 
  confitsus, 
  C. 
  I. 
  & 
  M. 
  

  

  A. 
  (S.) 
  argenteus, 
  Poir. 
  C. 
  eriodendroni, 
  C. 
  I. 
  & 
  M. 
  

  

  A. 
  (S.) 
  luteocephalus, 
  Newst. 
  C. 
  inomatipennis, 
  C. 
  I. 
  & 
  M. 
  

  

  A. 
  (0.) 
  apicoannnlatus 
  , 
  Edw. 
  C. 
  inomatipennis, 
  C. 
  I. 
  & 
  M., 
  var. 
  

  

  Toxorhynchites 
  brevipalpis, 
  Theo. 
  rutilus, 
  I. 
  & 
  M. 
  

  

  C. 
  pitnctithorax, 
  C. 
  I. 
  & 
  M. 
  

  

  Forcipomyia 
  ingrami, 
  Cart. 
  

  

  In 
  addition, 
  two 
  species 
  of 
  Psychodidae, 
  Telmatoscopas 
  meridionalis 
  and 
  a 
  small 
  

   species 
  not 
  yet 
  identified, 
  were 
  reared 
  from 
  material 
  from 
  this 
  particular 
  rot-hole, 
  

   one 
  large 
  species 
  of 
  Chironomidae, 
  and 
  two 
  species 
  of 
  Tipulidae 
  ; 
  a 
  species 
  of 
  

   cockroach 
  was 
  also 
  found 
  to 
  inhabit 
  this 
  rot-hole. 
  

  

  The 
  larvae 
  of 
  Anopheles 
  costalis, 
  Loew, 
  although 
  not 
  found 
  in 
  this 
  particular 
  tree 
  

   are 
  found 
  occasionally 
  in 
  rot-holes 
  in 
  trees 
  at 
  Accra. 
  

  

  Larvae 
  of 
  Stegomyia 
  are 
  especially 
  associated 
  with 
  rot-holes 
  in 
  trees. 
  In 
  a 
  flam- 
  

   boyant 
  tree 
  (Poinciana 
  rcgia) 
  in 
  the 
  laboratory 
  compound 
  there 
  is 
  a 
  rot-hole 
  which 
  is 
  

   permitted 
  to 
  remain 
  untouched 
  by 
  the 
  sanitary 
  authorities 
  on 
  condition 
  that 
  we 
  keep 
  

   close 
  watch 
  over 
  it. 
  From 
  this 
  rot-hole 
  we 
  have 
  obtained 
  Aedes 
  (Stegomyia) 
  apico- 
  

   argenteus, 
  Theo., 
  Aedes 
  argenteus, 
  Poir. 
  (S.fasciata, 
  F.), 
  Aedes 
  (S.) 
  luteocephalus, 
  Newst., 
  

   Aedes 
  (S.) 
  metallicus, 
  Edw., 
  Aedes 
  (S.) 
  simpsoni, 
  Theo., 
  and 
  Aedes 
  (S.) 
  unilineatus, 
  

   Theo. 
  — 
  that 
  is, 
  all 
  the 
  species 
  of 
  the 
  subgenus 
  Stegomyia 
  known 
  to 
  occur 
  in 
  Accra. 
  

  

  It 
  would 
  perhaps 
  be 
  more 
  accurate 
  to 
  describe 
  the 
  larvae 
  of 
  this 
  subgenus 
  

   as 
  frequenting 
  small 
  enclosed 
  collections 
  of 
  water, 
  since 
  they 
  are 
  by 
  no 
  means 
  restricted 
  

   to 
  rot-holes 
  in 
  trees. 
  Aedes 
  argenteus 
  (Stegomyia 
  fasciata), 
  indeed, 
  appears 
  to 
  have 
  

   become 
  largely 
  a 
  domestic 
  mosquito, 
  laving 
  its 
  eggs 
  in 
  the 
  vessels 
  which 
  accumulate 
  

   in 
  the 
  vicinity 
  of 
  human 
  habitations. 
  Far 
  from 
  the 
  haunts 
  of 
  man, 
  however, 
  larvae 
  

   of 
  this 
  species 
  are 
  abundant 
  not 
  only 
  in 
  rot-holes, 
  but 
  also 
  in 
  old 
  calabashes, 
  small 
  

   rock 
  pools, 
  and 
  similar 
  situations, 
  so 
  that 
  it 
  may 
  well 
  be 
  that 
  its 
  domestic 
  habit 
  is 
  

   less 
  an 
  adaptation 
  than 
  an 
  accidental 
  occurrence, 
  the 
  result 
  of 
  the 
  great 
  multiplication 
  

   in 
  and 
  around 
  towns 
  and 
  villages 
  (especially 
  those 
  to 
  which 
  European 
  civilisation 
  has 
  

   introduced 
  the 
  tin) 
  of 
  just 
  those 
  kinds 
  of 
  situation 
  which 
  the 
  mosquito 
  was 
  accustomed 
  

   to 
  select 
  as 
  favourable 
  for 
  the 
  development 
  of 
  its 
  larvae, 
  and 
  which, 
  moreover, 
  have 
  

   the 
  additional 
  advantage 
  that 
  they 
  are 
  not 
  frequented 
  by 
  its 
  natural 
  enemies. 
  Other 
  

   species 
  appear 
  to 
  be 
  more 
  particular 
  as 
  to 
  the 
  nature 
  of 
  their 
  nurseries, 
  for 
  example, 
  

   Aedes 
  (S.) 
  vittatus 
  shows 
  a 
  strong 
  preference 
  for 
  rock 
  pools, 
  and 
  we 
  have 
  not 
  found 
  

   A. 
  (S.) 
  metallicus 
  and 
  A. 
  (S.) 
  unilineatus 
  except 
  in 
  rot-holes 
  in 
  trees. 
  As 
  has 
  been 
  

   suggested 
  by 
  one 
  of 
  us 
  (Report 
  of 
  the 
  Accra 
  Laboratory 
  for 
  the 
  year 
  1916, 
  pp. 
  28-29), 
  

   the 
  resistant 
  eggs 
  of 
  Stegomyia 
  (and 
  such 
  resistant 
  eggs 
  are 
  not 
  peculiar 
  to 
  Aedes 
  

   argenteus) 
  are 
  an 
  adaptation 
  not 
  so 
  much 
  to 
  the 
  necessity 
  of 
  tiding 
  over 
  the 
  dry 
  

   season 
  as 
  to 
  the 
  habit 
  of 
  breeding 
  in 
  small 
  enclosed 
  collections 
  of 
  water, 
  such 
  as 
  rot- 
  

   holes, 
  which 
  are 
  apt 
  to 
  dry 
  up 
  between 
  rain 
  showers 
  by 
  evaporation 
  or 
  leakage, 
  

   leaving 
  the 
  eggs 
  that 
  had 
  been 
  deposited 
  on 
  the 
  surface 
  stranded 
  on 
  the 
  sides. 
  This 
  

   adaptation 
  not 
  only 
  saves 
  the 
  eggs 
  from 
  perishing, 
  but 
  also 
  gives 
  them 
  a 
  decided 
  

   advantage 
  over 
  newly 
  deposited 
  eggs, 
  for 
  whereas 
  eggs 
  laid 
  directly 
  on 
  the 
  water 
  

   take 
  a 
  few 
  days 
  (about 
  three 
  days 
  in 
  the 
  case 
  of 
  Aedes 
  argenteus) 
  to 
  hatch, 
  those 
  

   which 
  have 
  been 
  stranded 
  hatch 
  immediatelv 
  they 
  are 
  immersed 
  — 
  for 
  instance, 
  by 
  

   a 
  shower 
  filling 
  up 
  the 
  rot-hole 
  — 
  and 
  the 
  emerging 
  larvae 
  have 
  therefore 
  a 
  better 
  

   chance 
  of 
  completing 
  their 
  development 
  before 
  the 
  rot-hole 
  or 
  other 
  small 
  collection 
  

   of 
  water 
  dries 
  up 
  again. 
  

  

  