﻿140 
  REPORT 
  UNITED 
  STATES 
  ENTOMOLOGICAL 
  COMMISSION. 
  

  

  The 
  result 
  in 
  this 
  case 
  approximates 
  very 
  closely 
  to 
  that 
  at 
  Grand 
  

   Island, 
  if 
  we 
  take 
  60° 
  as 
  the 
  minimum. 
  As 
  the 
  data 
  in 
  reference 
  to 
  North 
  

   Platte 
  is 
  not 
  so 
  positive 
  as 
  that 
  in 
  reference 
  to 
  the 
  other 
  two, 
  we 
  may 
  take 
  

   the 
  latter 
  as 
  giving 
  approximately 
  the 
  length 
  of 
  exposure 
  to 
  a 
  given 
  

   degree 
  of 
  temperature 
  that 
  is 
  necessary 
  to 
  hatch 
  the 
  eggs 
  in 
  their 
  nat- 
  

   ural 
  position. 
  

  

  Taking 
  the 
  results 
  at 
  these 
  two 
  places 
  and 
  Mr. 
  Biley's 
  experiments, 
  

   let 
  us 
  from 
  them 
  test 
  Professor 
  Abbe's 
  u 
  working 
  basis." 
  Mr. 
  Riley 
  

   found 
  by 
  actual 
  experiment 
  that 
  at 
  a 
  temperature 
  of 
  85°, 
  from 
  28 
  to 
  33 
  — 
  

   say 
  31 
  days 
  — 
  744 
  hours 
  were 
  required 
  to 
  hatch 
  the 
  eggs 
  ; 
  that 
  at 
  a 
  tem- 
  

   perature 
  of 
  75° 
  — 
  42 
  days 
  — 
  1,008 
  hours 
  were 
  required. 
  By 
  taking 
  the 
  

   number 
  of 
  hours 
  at 
  which 
  they 
  were 
  exposed, 
  at 
  these 
  two 
  places, 
  to 
  a 
  

   temperature 
  between 
  50° 
  and 
  60°, 
  60° 
  and 
  75°, 
  and 
  above 
  75°, 
  to 
  wit, 
  

   Grand 
  Island, 
  784, 
  988, 
  and 
  240 
  hours, 
  respectively, 
  as 
  given 
  above, 
  and 
  

   Moorhead, 
  921, 
  1,411, 
  and 
  360 
  hours, 
  and 
  reducing 
  them 
  by 
  proportion 
  

   to 
  50° 
  and 
  60°, 
  we 
  obtain 
  the 
  following 
  results 
  : 
  

  

  The 
  time 
  required 
  to 
  hatch 
  the 
  eggs 
  at 
  a 
  uniform 
  temperature 
  of 
  85° 
  

   is 
  31 
  whole 
  days, 
  or 
  744 
  hours 
  5 
  at 
  75° 
  is 
  42 
  whole 
  days, 
  or 
  1,008 
  hours 
  ; 
  

   at 
  60° 
  is 
  60 
  whole 
  days, 
  or 
  1,440 
  hours 
  ; 
  at 
  50° 
  is 
  116 
  whole 
  days, 
  or 
  

   2,784 
  hours. 
  

  

  The 
  result 
  at 
  60° 
  is 
  precisely 
  that 
  given 
  by 
  Professor 
  Abbe, 
  the 
  dif- 
  

   ference 
  between 
  the 
  two 
  places 
  being 
  only 
  one 
  day 
  — 
  one 
  60 
  days, 
  the 
  

   other 
  61. 
  The 
  number 
  of 
  days 
  at 
  50° 
  in 
  the 
  average 
  of 
  112 
  and 
  120. 
  

  

  Notwithstanding 
  the 
  close 
  agreement 
  between 
  Mr. 
  Riley's 
  experi- 
  

   ments 
  and 
  Professor 
  Abbe's 
  theory, 
  there 
  are 
  so 
  many 
  elements 
  of 
  uncer- 
  

   tainty 
  entering 
  into 
  the 
  calculation 
  that 
  it 
  can 
  at 
  most 
  be 
  considered 
  

   but 
  as 
  a 
  means 
  of 
  approximating, 
  as 
  Professor 
  Abbe 
  truly 
  says, 
  the 
  fact. 
  

  

  If 
  the 
  hatching 
  depends 
  entirely 
  on 
  the 
  spring 
  temperature 
  and 
  not 
  

   on 
  the 
  sum 
  during 
  the 
  time 
  they 
  are 
  in 
  the 
  ground, 
  then 
  the 
  length 
  of 
  

   time 
  required 
  is 
  not 
  only 
  very 
  brief 
  but 
  is 
  by 
  no 
  means 
  uniform 
  5 
  but 
  

   the 
  results 
  of 
  the 
  foregoing 
  calculations 
  would 
  appear 
  to 
  render 
  it 
  cer- 
  

   tain 
  that 
  thesumis 
  a 
  necessary 
  factor, 
  and 
  for 
  bringing 
  this 
  out 
  we 
  must 
  

   thank 
  Professor 
  Abbe 
  ; 
  but 
  we 
  must 
  not 
  forget 
  that 
  time 
  also 
  is 
  a 
  factor 
  

   which 
  must 
  be 
  considered, 
  otherwise 
  the 
  southern 
  localities 
  ought 
  to 
  

   produce 
  two 
  broods 
  in 
  the 
  year. 
  

  

  The 
  direct 
  influence 
  of 
  the 
  temperature 
  and 
  winds 
  on 
  flights, 
  — 
  For 
  the 
  

   purpose 
  of 
  illustrating 
  this 
  we 
  introduce 
  here 
  the 
  daily 
  records 
  of 
  tem- 
  

   perature 
  and 
  wind 
  during 
  the 
  summer 
  of 
  1877. 
  It 
  is 
  limited 
  to 
  six 
  of 
  

   the 
  most 
  important 
  northwestern 
  stations, 
  and 
  has 
  been 
  kindly 
  fur- 
  

   nished 
  to 
  the 
  Commission 
  by 
  the 
  Chief 
  of 
  the 
  Signal 
  Service 
  Bureau, 
  to 
  

   whom 
  we 
  are 
  under 
  obligations 
  for 
  numerous 
  favors. 
  

  

  