﻿208 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  Natural 
  Agents 
  Controlling 
  the 
  Army-worm. 
  

  

  The 
  inquiries 
  are 
  frequently 
  made: 
  Where 
  do 
  the 
  army-worms 
  come 
  

   from 
  ? 
  Will 
  they 
  be 
  abundant 
  next 
  year 
  ? 
  The 
  first 
  question 
  has 
  already 
  

   been 
  answered, 
  but 
  the 
  answer 
  to 
  the 
  second 
  may 
  not 
  be 
  so 
  readily 
  

   given. 
  The 
  comparative 
  abundance 
  or 
  scarcity 
  of 
  this 
  insect, 
  as 
  well 
  as 
  

   of 
  others, 
  from 
  year 
  to 
  year 
  is 
  controlled 
  by 
  natural 
  causes. 
  The 
  most 
  

   prominent 
  of 
  these 
  are 
  the 
  relative 
  abundance 
  and 
  quality 
  of 
  its 
  food, 
  

   the 
  favorable 
  or 
  adverse 
  climatic 
  conditions, 
  and 
  the 
  number 
  and 
  activity 
  

   of 
  its 
  natural 
  enemies. 
  Temperature 
  and 
  moisture 
  have 
  an 
  important 
  

   bearing 
  on 
  the 
  production 
  of 
  its 
  food-plants, 
  and 
  all 
  know 
  that 
  without 
  

   an 
  amply 
  supply 
  of 
  proper 
  food, 
  the 
  caterpillars 
  would 
  die 
  while 
  yoimg 
  

   or 
  immature, 
  and 
  no 
  serious 
  injury 
  to 
  crops 
  would 
  result 
  from 
  their 
  

   presence. 
  Weather 
  conditions 
  have 
  also 
  marked 
  effect 
  upon 
  insect 
  

   growth 
  and 
  development. 
  Cold 
  and 
  wet 
  serve 
  to 
  impair 
  lepidopterous 
  

   life, 
  and 
  when 
  such 
  prevails 
  while 
  the 
  insect 
  is 
  in 
  its 
  tender 
  larval 
  stages, 
  

   great 
  mortahty 
  is 
  the 
  result. 
  Hibernation 
  is 
  a 
  severe 
  ordeal 
  for 
  many 
  

   insects, 
  and 
  alternate 
  freezings 
  and 
  thawings, 
  to 
  which 
  they 
  may 
  be 
  sub- 
  

   jected, 
  may 
  terminate 
  many 
  insect 
  lives. 
  It 
  is 
  only 
  when 
  the 
  climatic 
  

   conditions 
  in 
  connection 
  with 
  other 
  controlling 
  causes 
  are 
  favorable 
  

   to 
  the 
  rapid 
  growth 
  and 
  multipHcation 
  of 
  the 
  insect, 
  that 
  the 
  ravages 
  of 
  

   the 
  army-worm 
  reach 
  the 
  ruinous 
  extent 
  of 
  the 
  present 
  year. 
  Such 
  com- 
  

   binations 
  can 
  not 
  be 
  predicted. 
  They 
  very 
  rarely 
  occur 
  in 
  consecutive 
  

   years. 
  The 
  theory 
  has 
  been 
  advanced, 
  that 
  a 
  dry 
  season 
  followed 
  by 
  

   a 
  wet 
  one, 
  is 
  likely 
  to 
  be 
  an 
  army-worm 
  year, 
  and 
  it 
  is 
  apparently 
  borne 
  

   out 
  by 
  records 
  made. 
  But 
  the 
  attempt 
  to 
  predict 
  the 
  abundance 
  of 
  the 
  

   army-worm 
  solely 
  from 
  the 
  amount 
  of 
  rain-fall 
  for 
  the 
  year, 
  ignores 
  the 
  

   important 
  part 
  that 
  the 
  predaceous 
  and 
  parasitic 
  enemies 
  of 
  this 
  insect 
  

   have 
  in 
  its 
  control. 
  

  

  The 
  army-worm 
  is 
  also 
  subject 
  to 
  a 
  deadly 
  bacterial 
  disease, 
  which 
  may 
  

   be 
  fatal 
  to 
  large 
  numbers. 
  In 
  the 
  western 
  portion 
  of 
  the 
  State, 
  25 
  per 
  

   cent, 
  were 
  killed 
  by 
  it 
  in 
  some 
  localities 
  (Lowe, 
  loc 
  cit., 
  p. 
  128). 
  Unfortu- 
  

   nately, 
  the 
  disease 
  is 
  only 
  effective, 
  it 
  is 
  believed, 
  under 
  certain 
  conditions, 
  

   and 
  these 
  are 
  rarely 
  favorable 
  in 
  nature 
  to 
  any 
  extended 
  action, 
  or 
  even 
  

   to 
  artificial 
  propagation. 
  

  

  Predaceous 
  Enemies. 
  

  

  Fortunately 
  for 
  the 
  farmer, 
  the 
  army-worm 
  has 
  a 
  large 
  number 
  of 
  foes 
  

  

  that 
  prey 
  upon 
  it. 
  Swine 
  are 
  said 
  to 
  eat 
  them 
  greedily, 
  and 
  to 
  prefer 
  

  

  them 
  to 
  corn. 
  Shrews, 
  skunks, 
  and 
  weasels, 
  are 
  reported 
  as 
  consuming 
  

  

  large 
  numbers. 
  Domestic 
  fowls, 
  especially 
  ducks 
  and 
  geese, 
  are 
  valuable 
  

  

  