﻿94 
  

  

  The 
  bugs 
  were 
  most 
  abundant 
  in 
  the 
  lower 
  parts 
  of 
  the 
  field, 
  where, 
  

   in 
  fact, 
  they 
  had 
  dwarfed 
  the 
  wheat. 
  Many 
  young 
  were 
  now 
  clus- 
  

   tered 
  on 
  the 
  stems, 
  but 
  none 
  were 
  found 
  dead. 
  Adults 
  were 
  still 
  pair- 
  

   ing, 
  and 
  a 
  few 
  eggs 
  remained 
  unhatched. 
  

  

  The 
  month 
  closed 
  with 
  a 
  hot 
  wave, 
  the 
  maximum 
  temperature 
  

   reaching 
  95° 
  on 
  the 
  31st, 
  and 
  the 
  mean 
  temperature 
  of 
  the 
  last 
  three 
  

   days 
  ranging 
  from 
  75° 
  to 
  83°. 
  Similar 
  weather 
  continued 
  until 
  June 
  

   3, 
  at 
  which 
  time 
  the 
  field 
  was 
  again 
  examined 
  with 
  similar 
  results. 
  

   The 
  only 
  surface 
  moisture 
  observed 
  in 
  the 
  field 
  was 
  under 
  the 
  patches 
  

   of 
  trampled 
  wheat. 
  The 
  entire 
  contents 
  of 
  two 
  contagion 
  boxes 
  in 
  

   the 
  laboratory 
  were 
  at 
  this 
  time 
  sown 
  broadcast 
  in 
  the 
  wheat. 
  This 
  

   material 
  contained 
  several 
  hundred 
  chinch-bugs 
  dead 
  and 
  covered 
  

   with 
  Sporotrichum, 
  and 
  also 
  many 
  live 
  bugs 
  which 
  had 
  been 
  thor- 
  

   oughly 
  exj)osed 
  to 
  infection 
  in 
  the 
  contagion 
  boxes. 
  Many 
  fungiv- 
  

   orous 
  mites 
  were, 
  however, 
  distributed 
  with 
  this 
  material, 
  these 
  

   creatures 
  having 
  become 
  so 
  abundant 
  in 
  our 
  laboratory 
  cultures 
  as 
  to 
  

   compel 
  the 
  cleaning 
  out 
  and 
  renewal 
  of 
  the 
  culture 
  boxes. 
  Five 
  or 
  

   six 
  hundred 
  other 
  fungus-covered 
  bugs 
  obtained 
  from 
  Southern 
  Illi- 
  

   nois 
  fields 
  and 
  the 
  contents 
  of 
  three 
  culture 
  pans 
  and 
  six 
  fruit- 
  jar 
  

   cultures 
  were 
  likewise 
  distributed. 
  Two 
  days 
  later 
  several 
  hundred 
  

   dead 
  bugs 
  covered 
  with 
  Sporotrichum 
  and 
  many 
  living 
  ones 
  exposed 
  

   to 
  infection 
  were 
  scattered 
  broadcast 
  in 
  this 
  field. 
  A 
  trace 
  of 
  rain 
  

   fell 
  on 
  the 
  9th 
  and 
  two 
  thirds 
  of 
  an 
  inch 
  on 
  the 
  12th, 
  the 
  weather 
  

   otherwise 
  having 
  been 
  almost 
  continually 
  clear 
  and 
  usually 
  very 
  

   warm, 
  the 
  maximum 
  temperature 
  ranging 
  from 
  78° 
  on 
  the 
  5th 
  to 
  

   98.5° 
  on 
  the 
  10th, 
  the 
  minimum 
  from 
  42° 
  to 
  74°, 
  and 
  the 
  mean 
  from 
  

   66° 
  to 
  82°. 
  No 
  traces 
  of 
  fungus 
  infection 
  were 
  detected 
  in 
  this 
  field 
  

   on 
  the 
  18th, 
  even 
  the 
  artificial 
  culture 
  materials 
  soon 
  being 
  denuded 
  

   of 
  fungous 
  growth. 
  Chinch-bugs 
  were 
  quite 
  abundant, 
  mostly 
  in 
  the 
  

   first 
  three 
  molts, 
  but 
  none 
  were 
  found 
  dead. 
  The 
  ground 
  was 
  only 
  

   slightly 
  damp 
  from 
  the 
  rain 
  of 
  the 
  preceding 
  day. 
  

  

  The 
  next 
  examination 
  was 
  made 
  June 
  20, 
  only 
  .4 
  of 
  an 
  inch 
  of 
  rain 
  

   having 
  falling 
  in 
  the 
  interval. 
  The 
  ground 
  was 
  very 
  dry 
  to 
  a 
  depth 
  

   of 
  two 
  inches 
  or 
  more, 
  and 
  the 
  wheat 
  had 
  begun 
  to 
  ripen. 
  Bugs 
  of 
  

   the 
  hibernating 
  generatiori 
  were 
  now 
  probably 
  all 
  dead, 
  and 
  a 
  few 
  

   adults 
  of 
  the 
  new 
  generation 
  just 
  emerged 
  were 
  seen 
  among 
  the 
  

   great 
  numbers 
  of 
  young 
  in 
  the 
  first 
  three 
  stages 
  of 
  development. 
  

   Very 
  thorough 
  examination 
  was 
  made 
  of 
  all 
  parts 
  of 
  the 
  field 
  in 
  

   which 
  infected 
  material 
  had 
  been 
  distributed, 
  but 
  no 
  traces 
  of 
  dis- 
  

   ease 
  were 
  found 
  among 
  tlu^ 
  bugs, 
  nor 
  any 
  visible 
  traces 
  of 
  fungus 
  on 
  

   the 
  old 
  material 
  sown. 
  That 
  this 
  distributed 
  fungus 
  was 
  absolutely 
  

   killed, 
  if 
  not 
  destroyed, 
  was 
  shown 
  by 
  placing 
  portions 
  of 
  the 
  dried- 
  

   up 
  corn 
  meal 
  found 
  in 
  the 
  field 
  in 
  a 
  moist 
  chamber 
  under 
  conditions 
  

   favorable 
  to 
  the 
  revival 
  of 
  the 
  Sporotrichum 
  culture. 
  After 
  four 
  

   days 
  there 
  was 
  no 
  occurrence 
  of 
  any 
  such 
  growth, 
  only 
  Penicillium 
  

   and 
  two 
  s])ecies 
  of 
  Sterigmatocystis 
  appearing. 
  It 
  was 
  evident 
  at 
  

   this 
  point 
  not 
  only 
  that 
  the 
  distributions 
  made 
  had 
  failed 
  to 
  convey 
  

   disease 
  to 
  the 
  insects 
  in 
  the 
  field, 
  but 
  also 
  that 
  the 
  Sporotrichum 
  itself 
  

   had 
  completely 
  perished, 
  whether 
  as 
  a 
  consequence 
  of 
  exposure 
  

   to 
  heat 
  and 
  sun 
  or 
  devoured, 
  in 
  part 
  at 
  least, 
  by 
  fungus-eating 
  mites, 
  

   it 
  is 
  not 
  now 
  possible 
  to 
  say. 
  Later 
  in 
  the 
  season, 
  however, 
  after 
  

  

  