﻿HISTORY 
  OF 
  THE 
  DISEASES 
  IN 
  THE 
  UNITED 
  STATES. 
  209 
  

  

  even 
  though 
  the 
  germs 
  be 
  present; 
  while, 
  if 
  the 
  weather 
  be 
  favorable 
  to 
  the 
  growth 
  

   of 
  the 
  Empusa, 
  the 
  bugs 
  are 
  likely 
  to 
  be 
  swept 
  off 
  by 
  an 
  epidemic 
  of 
  the 
  disease, 
  

   whether 
  introduced 
  artificially 
  or 
  not, 
  as 
  the 
  germs 
  are 
  apparently 
  widely 
  distrib- 
  

   uted, 
  and 
  only 
  await 
  favorable 
  conditions 
  to 
  bring 
  them 
  into 
  action. 
  

  

  In 
  the 
  seventeenth 
  report 
  of 
  the 
  Illinois 
  State 
  Entomologist 
  (Professor 
  

   Forbes's 
  sixth 
  report) 
  for 
  1889 
  and 
  1890, 
  published 
  in 
  1891 
  (received 
  by 
  me 
  

   in 
  February, 
  1892), 
  Professor 
  Forbes 
  presents 
  an 
  article 
  entitled 
  "Notes 
  on 
  the 
  

   Diseases 
  of 
  the 
  Chinch-bug," 
  pp. 
  74-87. 
  In 
  a 
  foot-note 
  it 
  is 
  said 
  that 
  " 
  this 
  

   article 
  has 
  been 
  revised 
  in 
  passing 
  through 
  the 
  press 
  to 
  include 
  results 
  arrived 
  

   at 
  here 
  since 
  it 
  was 
  written, 
  and 
  it 
  is 
  now 
  substantially 
  complete 
  to 
  June 
  

   15, 
  1891. 
  The 
  opening 
  paragraphs 
  of 
  the 
  "Notes" 
  are 
  as 
  follows: 
  

  

  The 
  fact 
  that 
  the 
  almost 
  total 
  disappearance 
  in 
  1889 
  of 
  a 
  great 
  outbreak 
  of 
  the 
  

   chinch-bug 
  which 
  had 
  cost 
  Illinois 
  and 
  adjacent 
  States 
  many 
  millions 
  of 
  dollars 
  was 
  

   apparently 
  due 
  chiefly, 
  if 
  not 
  altogether, 
  to 
  parasitism 
  by 
  fungi, 
  or, 
  in 
  other 
  words, 
  

   to 
  contagious 
  insect 
  disease, 
  has 
  given 
  to 
  these 
  diseases 
  of 
  insects 
  a 
  very 
  special 
  in- 
  

   terest 
  and 
  importance 
  at 
  the 
  present 
  time; 
  and 
  possibly 
  successful 
  attempts 
  made 
  

   in 
  Minnesota, 
  Kansas 
  and 
  Indiana 
  for 
  the 
  transfer 
  of 
  one 
  of 
  them 
  to 
  previously 
  

   healthy 
  bugs, 
  and 
  even 
  for 
  its 
  dissemination 
  in 
  some 
  instances 
  to 
  fields 
  previously 
  

   free 
  from 
  them, 
  gives 
  to 
  researches 
  bearing 
  on 
  this 
  subject 
  a 
  great 
  and 
  permanent 
  

   practical 
  value. 
  . 
  . 
  . 
  

  

  We 
  have 
  at 
  present 
  positive 
  knowledge 
  of 
  two 
  diseases 
  of 
  the 
  chinch-bug, 
  and 
  

   highly 
  probable 
  evidence 
  of 
  a 
  third, 
  the 
  first 
  two 
  associated 
  with 
  the 
  occurrence 
  of 
  

   spore-bearing 
  fungi 
  (Entomophthora 
  and 
  Sjoorotrichum), 
  and 
  the 
  third 
  with 
  a 
  bacte- 
  

   rial 
  species 
  described 
  in 
  1883 
  as 
  Micrococcus 
  insectorum. 
  In 
  the 
  first 
  and 
  last 
  cases 
  we 
  

   lack 
  the 
  absolute 
  certainty 
  given 
  by 
  experimental 
  transfer 
  of 
  the 
  disease 
  by 
  means 
  

   of 
  its 
  characteristic 
  fungi 
  to 
  insects 
  shown 
  to 
  be 
  previously 
  free 
  from 
  it; 
  but 
  with 
  

   respect 
  to 
  the 
  first 
  of 
  these 
  affections, 
  that 
  connected 
  with 
  the 
  Entomophthora, 
  this 
  

   deficiency 
  has 
  little 
  meaning. 
  The 
  species 
  of 
  this 
  genus 
  are 
  so 
  generally 
  parasitic 
  

   on 
  insects, 
  and 
  the 
  nature 
  of 
  their 
  effect 
  upon 
  the 
  chinch-bug 
  is 
  so 
  unmistakable, 
  

   that 
  experimental 
  evidence 
  is 
  really 
  quite 
  unessential. 
  The 
  subject 
  of 
  the 
  bacterial 
  

   disease 
  is, 
  however, 
  a 
  much 
  more 
  difficult 
  and 
  intricate 
  one, 
  and 
  positive 
  assumption 
  

   of 
  the 
  pathogenic 
  character 
  of 
  any 
  given 
  microbe 
  is 
  always 
  unwarranted 
  unless 
  

   brought 
  to 
  the 
  test 
  of 
  precise 
  transfer 
  experiments. 
  

  

  Professor 
  Forbes 
  states 
  that 
  the 
  evidence 
  in 
  favor 
  of 
  a 
  bacterial 
  disease 
  of 
  

   the 
  chinch-bug 
  is 
  essentially 
  as 
  follows 
  : 
  

  

  First, 
  the 
  very 
  general 
  occurrence 
  of 
  vast 
  numbers 
  of 
  a 
  single 
  species 
  of 
  Micro- 
  

   coccus 
  in 
  the 
  coeca 
  of 
  the 
  alimentary 
  canal 
  of 
  chinch-bugs 
  evidently 
  suffering 
  from 
  

   disease, 
  accompanied 
  by 
  the 
  complete 
  destruction 
  of 
  the 
  epithelium 
  of 
  such 
  coeca, 
  

   at 
  a 
  time 
  when 
  an 
  enormous 
  mortality 
  was 
  apparent 
  among 
  them; 
  second, 
  the 
  ab- 
  

   sence 
  of 
  such 
  bacterial 
  affection 
  during 
  periods 
  of 
  normal 
  prosperity; 
  third, 
  a 
  vari- 
  

   ation, 
  generally 
  speaking, 
  in 
  the 
  number 
  of 
  these 
  Micrococci, 
  roughly 
  corresponding 
  

   to 
  the 
  evident 
  prevalence 
  and 
  intensity 
  of 
  fatal 
  disease; 
  and, 
  fourth, 
  the 
  death 
  by 
  

   disease, 
  with 
  an 
  abundance 
  of 
  the 
  above 
  Micrococcus 
  in 
  the 
  alimentary 
  canal, 
  of 
  

   chinch-bugs 
  previously 
  confined 
  as 
  an 
  experiment 
  with 
  selected 
  lots 
  known 
  to 
  be 
  

   perishing 
  in 
  like 
  manner, 
  checks 
  composed 
  of 
  specimens 
  not 
  so 
  exposed 
  remaining, 
  

   in 
  the 
  meantime, 
  unaffected. 
  

  

  As 
  to 
  the 
  Sporotrichum 
  disease, 
  Professor 
  Forbes 
  sums 
  up 
  as 
  follows 
  : 
  

   That 
  the 
  fungus 
  here 
  called 
  a 
  Sporotrichum 
  (S. 
  globuliferum 
  Spegazzini, 
  accord- 
  

   ing 
  to 
  Peck) 
  is 
  likewise 
  a 
  cause 
  of 
  spontaneous 
  disease 
  among 
  chinch-bugs, 
  is 
  in- 
  

  

  