﻿436 
  W. 
  F. 
  FISKE. 
  

  

  is 
  necessary 
  to 
  deprive 
  the 
  fly 
  of 
  protection 
  in 
  any 
  event 
  (before 
  its 
  destructors 
  can 
  

   be 
  utilised) 
  and 
  knowledge 
  of 
  protective 
  factors 
  in 
  its 
  bionomics 
  must 
  be 
  acquired 
  

   sooner 
  or 
  later. 
  

  

  The 
  deprivative 
  factors 
  in 
  the 
  bionomics 
  of 
  Glossina 
  appear, 
  on 
  the 
  whole, 
  to 
  be 
  

   more 
  efficacious 
  in 
  restricting 
  its 
  range 
  and 
  density 
  than 
  the 
  destructive. 
  They 
  

   include 
  all 
  the 
  destructive 
  and 
  otherwise 
  inimical 
  factors 
  in 
  the 
  bionomics 
  of 
  its 
  

   host 
  species, 
  and, 
  in 
  addition, 
  whatever 
  else 
  may 
  operate 
  to 
  render 
  its 
  food 
  supply 
  

   less 
  easily 
  accessible 
  or 
  available. 
  But 
  the 
  many 
  deprivative 
  factors 
  are 
  as 
  difficult 
  

   to 
  identify 
  and 
  define 
  as 
  the 
  destructive, 
  and 
  it 
  is 
  simpler 
  and 
  more 
  practical 
  to 
  

   study 
  the 
  more 
  specific 
  food 
  factors 
  than 
  to 
  attempt 
  to 
  identify 
  and 
  study 
  the 
  less 
  

   specific 
  destructors 
  or 
  deprivators 
  of 
  food. 
  

  

  In 
  short, 
  except 
  as 
  a 
  matter 
  of 
  curiosity 
  or 
  technical 
  interest, 
  or 
  as 
  it 
  may 
  assist, 
  

   sometimes, 
  in 
  confirming 
  conclusions 
  or 
  supplementing 
  evidence 
  bearing 
  on 
  doubtful 
  

   points, 
  it 
  appears 
  neither 
  necessary 
  nor 
  desirable 
  to 
  devote 
  time 
  and 
  energy 
  to 
  

   investigation 
  into 
  the 
  identity 
  and 
  nature 
  of 
  the 
  factors 
  inimical 
  to 
  Glossina 
  palpalis. 
  

   If 
  the 
  object 
  for 
  investigation 
  into 
  its 
  bionomics 
  was 
  to 
  cultivate 
  it, 
  as 
  a 
  beneficial 
  

   species, 
  there 
  would 
  be 
  the 
  same 
  object 
  for 
  studying 
  its 
  enemies 
  that 
  there 
  is 
  for 
  

   studying 
  it 
  as 
  an 
  enemy 
  of 
  domestic 
  animals 
  or 
  human 
  populations, 
  namely, 
  to 
  find 
  

   means 
  of 
  protection 
  where 
  protection 
  is 
  lacking. 
  But 
  inasmuch 
  as 
  the 
  object 
  is 
  to 
  

   destroy 
  and 
  not 
  to 
  cultivate 
  it, 
  and 
  because, 
  obviously, 
  it 
  is 
  protected 
  against 
  all 
  its 
  

   destructors 
  and 
  other 
  inimical 
  factors 
  in 
  the 
  districts 
  which 
  it 
  infests, 
  it 
  appears 
  

   much 
  the 
  more 
  logical 
  as 
  well 
  as 
  the 
  simpler 
  and 
  easier 
  course 
  to 
  limit 
  all 
  specialised 
  

   or 
  intensive 
  studies 
  to 
  the 
  factors 
  responsible 
  for 
  its 
  presence 
  rather 
  than 
  to 
  attempt 
  

   inclusion 
  of 
  factors 
  manifestly 
  unable 
  to 
  prevent 
  its 
  presence 
  in 
  injurious 
  density. 
  

   On 
  the 
  face 
  of 
  it, 
  destructive 
  factors 
  are 
  locally 
  impotent 
  and 
  inoperative, 
  and 
  the 
  

   reason 
  for 
  this 
  must 
  be 
  found 
  before 
  they 
  can 
  be 
  made 
  operative 
  and 
  useful 
  ; 
  if 
  it 
  

   can 
  be 
  learned 
  how 
  the 
  pest 
  is 
  protected 
  against 
  them 
  it 
  may 
  be 
  possible 
  to 
  deprive 
  

   it 
  of 
  such 
  protection 
  and 
  thus 
  to 
  make 
  practical 
  utilisation 
  of 
  them, 
  but 
  not 
  otherwise. 
  

  

  On 
  these 
  accounts 
  relatively 
  little 
  attention 
  was 
  devoted 
  to 
  the 
  inimical 
  factors 
  

   in 
  the 
  bionomics 
  of 
  Glossina 
  palpalis. 
  A 
  few 
  experiments 
  were 
  made, 
  and 
  these, 
  

   together 
  with 
  a 
  summary 
  of 
  miscellaneous 
  observations 
  covering 
  a 
  very 
  wide 
  diversity 
  

   of 
  enemy 
  species, 
  are 
  cited 
  in 
  the 
  following 
  pages. 
  

  

  IX 
  (a). 
  The 
  Hosts 
  of 
  the 
  Fly 
  as 
  Destructive 
  Factors 
  in 
  its 
  Bionomics. 
  

  

  The 
  bite 
  of 
  the 
  tsetse 
  is 
  frequently 
  painful 
  enough 
  to 
  invite 
  vigorous 
  retaliation 
  

   on 
  the 
  part 
  of 
  any 
  but 
  the 
  thicker 
  skinned 
  and 
  least 
  sensitive 
  host 
  animals, 
  and 
  an 
  

   active, 
  sensitive 
  host 
  would 
  thus 
  become 
  a 
  destructive 
  enemy 
  of 
  the 
  first 
  importance 
  

   if 
  the 
  flies 
  were 
  forced 
  to 
  feed 
  upon 
  it, 
  or 
  were 
  foolish 
  enough 
  to 
  press 
  their 
  attack 
  

   upon 
  it 
  regardless 
  of 
  consequences.* 
  It 
  is 
  not 
  improbable, 
  however, 
  that 
  the 
  tsetse 
  is 
  

  

  *The 
  very 
  active 
  and 
  very 
  sensitive 
  host 
  is 
  as 
  much 
  an 
  enemy 
  of 
  the 
  flies 
  as 
  any 
  

   parasite 
  or 
  predatory 
  destructor 
  known. 
  There 
  are 
  many 
  parasites 
  and 
  predators 
  which 
  

   would 
  destroy 
  the 
  flies 
  if 
  they 
  did 
  not 
  employ 
  self-protective 
  tactics 
  against 
  them 
  ; 
  

   there 
  are 
  several 
  species 
  of 
  host 
  animals 
  which 
  would 
  do 
  the 
  same 
  if 
  the 
  flies 
  were 
  

   devoid 
  of 
  self 
  -protective 
  instincts. 
  The 
  flies 
  are 
  actually 
  exterminated 
  by 
  neither 
  because 
  

   of 
  specialised 
  instincts 
  of 
  self-preservation. 
  

  

  