﻿PEOCEEDINGS 
  OF 
  THE 
  FOURTH 
  ENTO^fOT.OGICAL 
  MEETING 
  375 
  

  

  produce 
  a 
  crop 
  at 
  a 
  season 
  unfavourable 
  to 
  the 
  insect 
  pest, 
  the 
  use 
  of 
  

   trap 
  crops, 
  the 
  encouragement 
  of 
  parasites 
  and 
  predators, 
  and 
  the 
  

   employment 
  of 
  light 
  traps 
  and 
  attractive 
  baits. 
  The 
  last 
  four 
  may 
  be 
  

   noted. 
  Many 
  phytophagous 
  insects 
  (but 
  not 
  all) 
  will 
  attack 
  a 
  weakly 
  

   plant 
  rather 
  than 
  a 
  healthy 
  one, 
  but 
  no 
  degree 
  of 
  cultivation 
  can 
  prevent 
  

   attack 
  in 
  the 
  event 
  of 
  anything 
  in 
  the 
  nature 
  of 
  a 
  serious 
  invasion 
  ; 
  

   the 
  use 
  of 
  trap 
  crops 
  is 
  a 
  valuable 
  device 
  on 
  the 
  right 
  lines, 
  but 
  its 
  employ- 
  

   ment 
  is 
  limited 
  by 
  agricultural 
  conditions 
  and 
  lack 
  of 
  precisely 
  that 
  

   kind 
  of 
  knowledge 
  which 
  research 
  in 
  the 
  directions 
  I 
  have 
  suggested 
  

   would 
  supply. 
  In 
  attempting 
  to 
  increase 
  the 
  incidence 
  of 
  parasitism 
  

   or 
  predation 
  upon 
  a 
  given 
  species 
  of 
  insect 
  we 
  are 
  plunged 
  at 
  once 
  into 
  

   a 
  complex 
  web 
  of 
  inter-relations 
  that 
  demand 
  a 
  great 
  deal 
  of 
  patient 
  

   and 
  difficult 
  work 
  for 
  their 
  proper 
  undersanding 
  ; 
  between 
  every 
  para- 
  

   site 
  and 
  its 
  host 
  there 
  exists 
  an 
  equilibrium 
  dependent 
  upon 
  the 
  amount 
  

   of 
  food 
  available 
  for 
  each, 
  and 
  while 
  by 
  artificial 
  means 
  we 
  may 
  shift 
  

   this 
  equilibrium 
  temporarily 
  in 
  a 
  given 
  area, 
  to 
  shift 
  it 
  permanently 
  

   demands 
  constant 
  watchfullness 
  and 
  a 
  wide 
  and 
  efficient 
  organizatixDn 
  ; 
  

   light 
  traps 
  are 
  effective 
  for 
  the 
  capture 
  of 
  certain 
  insects, 
  but 
  in 
  spite 
  

   of 
  the 
  excellent 
  work 
  done 
  by 
  Loeb 
  and 
  others 
  the 
  action 
  of 
  light 
  on 
  

   nocturnal 
  insects 
  is 
  not 
  yet 
  understood, 
  and 
  the 
  conditions 
  which 
  largely 
  

   affect 
  the 
  practical 
  utility 
  of 
  the 
  method 
  are 
  still 
  unknown 
  : 
  the 
  same 
  

   thing 
  may 
  be 
  said 
  of 
  the 
  use 
  of 
  attractive 
  baits 
  ; 
  these 
  are 
  still 
  in 
  the 
  

   " 
  treacle-and-beer 
  " 
  stage, 
  and 
  it 
  is 
  unnecesary 
  to 
  insist 
  further 
  that 
  

   there 
  exists 
  here 
  an 
  opening 
  for 
  research 
  of 
  remarkable 
  interest 
  and 
  

   great 
  economic 
  importance. 
  

  

  When 
  we 
  consider 
  these 
  methods 
  as 
  a 
  whole, 
  and 
  tliink 
  of 
  the 
  apparent 
  

   multitudinous 
  complexity 
  of 
  the 
  web 
  of 
  insect 
  life 
  which 
  covers 
  the 
  

   surface 
  of 
  the 
  earth, 
  our 
  task 
  of 
  controlling 
  the 
  j)attern 
  of 
  the 
  web 
  with 
  

   such 
  instruments 
  must 
  often 
  seem 
  discouraging 
  in 
  its 
  magnitude. 
  If 
  

   werare 
  right 
  in 
  regarding 
  the 
  majority 
  of 
  insects 
  as 
  being 
  for 
  practical 
  

   purposes 
  mere 
  creatures 
  of 
  their 
  environment, 
  " 
  somnambulists 
  " 
  swayed 
  

   and 
  controlled 
  by 
  invisible 
  threads, 
  subtle 
  and 
  delicate, 
  but 
  definite 
  

   and 
  discoverable, 
  then, 
  instead 
  of 
  beating 
  at 
  the 
  elastic 
  face 
  of 
  the 
  web 
  

   and 
  striving 
  to 
  break 
  the 
  pattern 
  by 
  sheer 
  weight 
  and 
  force, 
  we 
  may 
  be 
  

   able 
  to 
  get 
  hold 
  of 
  the 
  threads 
  themselves 
  and 
  weave 
  a 
  pattern 
  to 
  our 
  

   own 
  liking. 
  

  

  [Mr. 
  Howlett 
  is 
  no^v, 
  alas, 
  no 
  more, 
  and 
  all 
  he 
  hoped 
  to 
  do 
  remains 
  

   undone. 
  I 
  am 
  indebted 
  to 
  Mr. 
  tS. 
  K. 
  Sen 
  of 
  his 
  Staff 
  for 
  the 
  following 
  

   notes 
  on 
  some 
  of 
  the 
  lines 
  of 
  work 
  which 
  are 
  being 
  prosecuted 
  in 
  the 
  

   attempt 
  to 
  solve 
  some 
  of 
  the 
  problems 
  he 
  outlined 
  in 
  the 
  foregoing 
  

   paper, 
  which 
  are 
  given 
  in 
  the 
  ho])c 
  that 
  some 
  investigator 
  with 
  a 
  bent 
  

   towards 
  this 
  line 
  of 
  work 
  may 
  perhaps 
  carry 
  them 
  on. 
  For 
  convenience 
  

  

  2 
  B 
  2 
  

  

  