﻿PROCEEDINGS 
  OF 
  THE 
  FOURTH 
  ENIOMOLOGICAL 
  MEETING 
  161 
  

  

  and 
  the 
  rains 
  on 
  account 
  of 
  the 
  heat 
  which 
  is 
  above 
  the 
  temperature 
  of 
  

   effective 
  rearing 
  of 
  either 
  the 
  host 
  or 
  its 
  parasite. 
  It 
  was 
  therefore 
  

   decided 
  to 
  try 
  to 
  control 
  its 
  aestivation 
  and 
  emergence 
  if 
  possible 
  by 
  

   artificially 
  regulating 
  the 
  moisture 
  and 
  temperature 
  conditions 
  of 
  its 
  

   surroundings. 
  It 
  may 
  be 
  said 
  that 
  as 
  regards 
  temperature 
  there 
  is 
  for 
  

   each 
  insect 
  (or 
  animal) 
  a 
  certain 
  degree 
  of 
  heat 
  which 
  is 
  most 
  favourable 
  

   to 
  its 
  well 
  being 
  and 
  obviously 
  every 
  rise 
  or 
  fall 
  of 
  temperature 
  above 
  or 
  

   below 
  this 
  point 
  must 
  to 
  a 
  certain 
  extent 
  be 
  injurious 
  to 
  it. 
  It 
  may 
  

   be 
  also 
  taken 
  as 
  granted 
  that 
  the 
  well 
  being 
  of 
  an 
  insect 
  depends 
  far 
  more 
  

   essentially 
  on 
  the 
  variations 
  and 
  extremes 
  of 
  temperature 
  than 
  on 
  the 
  

   absolute 
  degree 
  of 
  heat. 
  From 
  the 
  very 
  freezing 
  point, 
  a 
  rising 
  tem- 
  

   perature 
  begins 
  to 
  exert 
  its 
  stimulating 
  influence 
  on 
  the 
  vital 
  functions 
  

   of 
  every 
  living 
  thing 
  up 
  to 
  a 
  certain 
  point 
  when 
  the 
  functions 
  are 
  at 
  the 
  

   highest 
  possible 
  stress 
  under 
  the 
  optimum 
  temperature 
  which 
  of 
  course 
  is 
  

   different 
  in 
  different 
  animals. 
  If 
  the 
  heat 
  rises 
  above 
  this 
  optimum, 
  

   the 
  effects 
  are 
  reversed, 
  the 
  functional 
  activity 
  is 
  more 
  or 
  less 
  reduced 
  

   till 
  at 
  last 
  a 
  comatose 
  condition 
  is 
  reached 
  just 
  preceding 
  the 
  death 
  of 
  

   the 
  organism, 
  which 
  ensues 
  under 
  too 
  great 
  heat. 
  The 
  same 
  may 
  be 
  

   said 
  to 
  be 
  practically 
  the 
  case 
  with 
  humidity. 
  Its 
  effect 
  on 
  the 
  speed 
  

   of 
  animal 
  metabolism 
  is 
  extremely 
  variable 
  and 
  different 
  insects 
  have 
  

   probably 
  different 
  optimum 
  points 
  of 
  humidity. 
  In 
  many 
  cases 
  

   moist 
  air 
  is 
  known 
  to 
  retard 
  the 
  development 
  of 
  insects 
  while 
  in 
  others 
  

   it 
  seems 
  to 
  hasten 
  it. 
  From 
  a 
  large 
  number 
  of 
  observations 
  made 
  on 
  

   parasite 
  cocoons 
  under 
  different 
  temperature 
  conditions 
  in 
  the 
  Insectary 
  

   it 
  has 
  been 
  seen 
  that 
  at 
  about 
  80°F. 
  (this 
  is 
  the 
  mean 
  of 
  the 
  

   maximum 
  temperature 
  for 
  two 
  weeks 
  preceding 
  the 
  emergence 
  

   from 
  the 
  cocoon) 
  the 
  functional 
  activity 
  of 
  the 
  parasite 
  pupa 
  is 
  the 
  

   greatest 
  and 
  the 
  length 
  of 
  the 
  pupal 
  stage 
  under 
  such 
  condition 
  is 
  

   5 
  days. 
  If 
  the 
  temperature 
  goes 
  higher 
  the 
  grub 
  within 
  becomes 
  

   dormant 
  and 
  if 
  it 
  falls 
  below 
  it 
  the 
  pupal 
  period 
  gradually 
  

   lengthens 
  out 
  until 
  at 
  53°F. 
  it 
  is 
  as 
  long 
  as 
  58 
  days. 
  The 
  relation 
  

   between 
  temperature 
  and 
  the 
  length 
  of 
  pupal 
  stage 
  is 
  shown 
  in 
  the 
  

   graph. 
  (Plate 
  XXVIII). 
  Unfortunately 
  it 
  has 
  not 
  been 
  found 
  prac- 
  

   ticable 
  to 
  maintain 
  the 
  mean 
  of 
  the 
  maximum 
  temperature 
  at 
  a 
  point 
  

   considerably 
  below 
  53°F. 
  in 
  which 
  case 
  it 
  might 
  have 
  been 
  possible 
  to 
  

   determine 
  the 
  lower 
  temperature 
  limit 
  for 
  the 
  functional 
  activity 
  of 
  the 
  

   parasite. 
  As 
  regards 
  the 
  higher 
  limit 
  it 
  has 
  been 
  seen 
  that 
  when 
  the 
  

   temperature 
  is 
  allowed 
  to 
  rise 
  above 
  85°F. 
  the 
  emergence 
  of 
  parasites 
  

   from 
  cocoons 
  completely 
  stops. 
  This 
  is 
  clearly 
  shown 
  in 
  the 
  graph 
  

   (Plate 
  XXVIII), 
  in 
  which 
  the 
  curve 
  representing 
  the 
  lengths 
  of 
  the 
  pupal 
  

   stages 
  of 
  a 
  certain 
  number 
  of 
  insect 
  has 
  been 
  compared 
  with 
  that 
  re- 
  

   presenting 
  the 
  corresponding 
  temperatures 
  influencing 
  the 
  same. 
  The 
  

  

  