﻿RELATION 
  OF 
  TEMPERATURE, 
  ETC., 
  TO 
  LOCUST 
  FLIGHTS. 
  155 
  

  

  The 
  best 
  way 
  in 
  which 
  we 
  can 
  show 
  the 
  relation 
  between 
  the 
  flights 
  

   and 
  the 
  temperature 
  and 
  wind, 
  is 
  to 
  compare 
  statements 
  in 
  our 
  First 
  

   Report 
  with 
  this 
  table, 
  which 
  was 
  made 
  out 
  after 
  the 
  report 
  was 
  printed 
  ; 
  

   all 
  the 
  statements 
  relate 
  to 
  1877. 
  

  

  At 
  page 
  17:2 
  it 
  is 
  stated 
  that 
  the 
  first 
  flight 
  observed 
  in 
  Iowa 
  was 
  June 
  

   14. 
  from 
  the 
  south, 
  and 
  that 
  the 
  locusts 
  came 
  dozen 
  in 
  the 
  vicinity 
  of 
  Sioux 
  

   City, 
  in 
  the 
  extreme 
  northwest 
  part, 
  where 
  they 
  remained 
  some 
  days. 
  By 
  

   reference 
  to 
  the 
  Yankton 
  column, 
  it 
  appears 
  that 
  the 
  temperature 
  rose 
  on 
  

   the 
  13th 
  and 
  14th, 
  and 
  fell 
  again 
  on 
  the 
  15th; 
  the 
  wind 
  was 
  from 
  the 
  

   north 
  until 
  the 
  14th, 
  when 
  it 
  changed 
  and 
  blew 
  from 
  the 
  south, 
  wheeling 
  

   again 
  in 
  the 
  evening 
  to 
  the 
  north. 
  On 
  the 
  10th 
  it 
  was 
  again 
  from 
  the 
  

   south, 
  and 
  the 
  temperature 
  again 
  rose, 
  and 
  this 
  condition 
  continued 
  

   through 
  the 
  17th. 
  By 
  reference 
  to 
  page 
  173, 
  it 
  will 
  be 
  seen 
  there 
  was 
  a 
  

   heavy 
  flight 
  northward 
  across 
  the 
  southeastern 
  counties 
  of 
  Dakota. 
  

   This 
  is 
  one 
  out 
  of 
  hundreds 
  of 
  similar 
  cases 
  which 
  show 
  not 
  only 
  the 
  re- 
  

   lation 
  between 
  the 
  temperature 
  and 
  flights, 
  but 
  that 
  the 
  locusts 
  are 
  not 
  

   easily 
  turned 
  back 
  by 
  adverse 
  winds 
  when 
  they 
  start 
  in 
  a 
  given 
  direc- 
  

   tion 
  — 
  though 
  in 
  1877 
  this 
  was 
  not 
  so 
  marked 
  as 
  is 
  usually 
  the 
  case. 
  In- 
  

   vading 
  swarms 
  from 
  the 
  permanent 
  breeding 
  grounds 
  will 
  come 
  down 
  

   and 
  remain 
  for 
  days 
  waiting 
  for 
  the 
  wind 
  to 
  blow 
  in 
  the 
  right 
  direction, 
  

   and 
  seldom, 
  if 
  ever, 
  are 
  turned 
  back. 
  With 
  local 
  flights, 
  to 
  which 
  cate- 
  

   gory 
  those 
  of 
  1877 
  chiefly 
  belong, 
  the 
  case 
  is 
  different. 
  The 
  fall 
  in 
  tem- 
  

   perature 
  has 
  much 
  to 
  do 
  with 
  their 
  coming 
  down, 
  as 
  in 
  the 
  case 
  just 
  

   given, 
  as 
  we 
  find 
  that 
  afterwards 
  those 
  which 
  went 
  northward 
  did 
  gen- 
  

   erally 
  return 
  southward 
  in 
  1877 
  ; 
  but 
  the 
  case 
  was 
  different 
  in 
  1876. 
  

  

  From 
  July 
  2 
  to 
  7 
  the 
  weather 
  was 
  excessively 
  warm, 
  as 
  will 
  be 
  seen 
  

   by 
  reference 
  to 
  the 
  records 
  for 
  Yankton 
  and 
  North 
  Platte, 
  and 
  the 
  direc- 
  

   tion 
  of 
  the 
  wind 
  was 
  west 
  or 
  northwest. 
  By 
  turning 
  to 
  the 
  record 
  of 
  

   flights 
  for 
  1877 
  (appendix, 
  168-173), 
  it 
  will 
  be 
  seen 
  that 
  these 
  were 
  the 
  

   days 
  of 
  the 
  great 
  flights 
  to 
  the 
  west 
  and 
  northwest, 
  the 
  air 
  being 
  full 
  of 
  

   locusts 
  over 
  Minnesota, 
  Northern 
  Iowa, 
  Dakota, 
  and 
  Nebraska. 
  

  

  Page 
  174: 
  u 
  July 
  8.— 
  Swarms 
  returning, 
  moving 
  generally 
  a 
  little 
  east 
  

   of 
  south." 
  Compare 
  this, 
  which 
  applies 
  to 
  Minnesota 
  and 
  Dakota, 
  with 
  

   records 
  of 
  Bismarck, 
  Yankton, 
  and 
  North 
  Platte 
  for 
  July 
  8. 
  

  

  It 
  is 
  unnecessary 
  for 
  us 
  to 
  add 
  more 
  illustrations, 
  as 
  the 
  readers 
  can 
  

   compare 
  the 
  records 
  of 
  flights 
  as 
  given 
  in 
  our 
  First 
  Report 
  with 
  this 
  

   meteorological 
  table 
  for 
  themselves. 
  It 
  appears 
  from 
  a 
  careful 
  com- 
  

   parison 
  of 
  this 
  kind 
  that 
  whenever 
  the 
  maximum 
  temperature 
  falls 
  be- 
  

   low 
  70° 
  and 
  the 
  minimum 
  below 
  60° 
  that 
  there 
  is 
  no 
  flying. 
  See 
  for 
  

   illustration 
  the 
  records 
  of 
  flights, 
  July 
  18 
  and 
  19, 
  appendix, 
  p. 
  [182], 
  

   so 
  far 
  as 
  it 
  relates 
  to 
  Dakota, 
  and 
  compare 
  with 
  the 
  Bismarck 
  record 
  in 
  

   the 
  table 
  for 
  the 
  same 
  dates. 
  

  

  