﻿216 
  REPORT 
  UNITED 
  STATES 
  ENTOMOLOGICAL 
  COMMISSION. 
  

  

  and 
  tlie 
  following 
  crop 
  can 
  scarcely 
  be 
  estimated. 
  But 
  if 
  dry 
  weather 
  prevails 
  from 
  

   this 
  time 
  to 
  harvest, 
  the 
  damage 
  done 
  can 
  hardly 
  he 
  considerable 
  — 
  and 
  if 
  it 
  should 
  

   turn 
  very 
  dry 
  and 
  hot, 
  all 
  danger 
  from 
  serious 
  depredations 
  from 
  it 
  may 
  be 
  cast 
  out 
  

   of 
  the 
  account, 
  in 
  measuring 
  the 
  outcome 
  of 
  the 
  crop 
  — 
  since 
  a 
  certain 
  amount 
  of 
  

   moisture 
  is 
  absolutely 
  necessary 
  for 
  the 
  successful 
  development 
  of 
  the 
  several 
  stages 
  

   in 
  the 
  growth 
  and 
  progress 
  of 
  this 
  insect 
  scourge. 
  But 
  then 
  Professor 
  Riley 
  warned 
  

   me 
  against 
  drawing 
  final 
  conclusions 
  on 
  insufficient 
  data, 
  it 
  being 
  quite 
  possible 
  that 
  

   other 
  forces 
  and 
  causes 
  appearing 
  might 
  bring 
  about 
  a 
  quite 
  different 
  and 
  unexpected 
  

   result. 
  Nevertheless, 
  there 
  are 
  many 
  reasons 
  for 
  expecting 
  a 
  dry 
  spring, 
  a 
  warm 
  

   harvest, 
  and 
  a 
  hot 
  summer, 
  and 
  comparatively 
  trifling 
  damage 
  to 
  be 
  done 
  by 
  the 
  fly 
  

   on 
  the 
  wheat 
  harvest 
  of 
  1878.— 
  W. 
  J. 
  F. 
  

  

  The 
  effects 
  of 
  drouglit 
  on 
  the 
  Hessian 
  fly 
  has 
  been 
  noticed 
  by 
  Profes- 
  

   sor 
  Eiley, 
  in 
  the 
  American 
  Naturalist 
  for 
  November 
  1881^ 
  as 
  follows: 
  

  

  It 
  has 
  long 
  been 
  known 
  that 
  the 
  Hessian 
  Fly 
  flourishes 
  most 
  when 
  the 
  Chinch 
  Bug 
  

   flourishes 
  least; 
  in 
  other 
  words, 
  that 
  wet 
  weather 
  favors 
  it. 
  Moisture 
  seems 
  essen- 
  

   tial 
  to 
  the 
  well-being 
  of 
  the 
  larva. 
  The 
  prejudicial 
  effect 
  of 
  drought 
  has 
  not 
  hitherto 
  

   been 
  observed, 
  that 
  we 
  are 
  aware 
  of, 
  but 
  was 
  very 
  noticeable 
  the 
  present 
  year 
  in 
  

   parts 
  of 
  Ohio, 
  where 
  the 
  puparia 
  literally 
  dried 
  up. 
  Our 
  attention 
  was 
  first 
  called 
  to 
  

   the 
  fact 
  of 
  the 
  general 
  death 
  of 
  the 
  insect 
  in 
  the 
  "flaxseed" 
  state 
  by 
  Mr. 
  E. 
  W. 
  Clay- 
  

   pole, 
  of 
  Yellow 
  Springs, 
  Ohio, 
  and 
  our 
  observations 
  subsequently 
  coufirmed 
  his 
  experi- 
  

   ence. 
  The 
  intense 
  heat 
  had 
  not 
  only 
  desiccated 
  the 
  Cecidomyia, 
  but, 
  what 
  is 
  still 
  

   more 
  remarkable, 
  in 
  most 
  cases 
  the 
  parasites 
  also. 
  We 
  should 
  like 
  to 
  hear 
  from 
  Pro- 
  

   fessor 
  Cook, 
  of 
  Michigan, 
  and 
  others, 
  whether 
  a 
  like 
  result 
  followed 
  the 
  severe 
  heat 
  

   and 
  drought 
  in 
  other 
  parts 
  of 
  the 
  West. 
  The 
  presumption 
  is 
  that 
  the 
  mortality 
  was 
  

   general 
  and 
  that 
  farmers 
  may 
  expect 
  immunity 
  from 
  injury 
  for 
  some 
  years 
  to 
  come. 
  

  

  That 
  this 
  fly 
  flourishes 
  best 
  in 
  a 
  rather 
  warm 
  and 
  moist 
  season 
  is 
  

   shown 
  by 
  its 
  habits. 
  The 
  flies 
  hover 
  in 
  the 
  spring 
  and 
  autumn 
  over 
  the 
  

   wheat-fields 
  in 
  countless 
  numbers, 
  especially 
  at 
  morniug 
  and 
  evening, 
  

   avoiding 
  the 
  direct 
  heat 
  of 
  the 
  sun. 
  

  

  PARASITES 
  OF 
  THE 
  HESSIAN 
  FLY. 
  

  

  How 
  useful, 
  nay 
  indispensable, 
  parasitic 
  insects 
  may 
  prove 
  in 
  keeping 
  

   the 
  noxious 
  ones 
  within 
  due 
  limits 
  is 
  well 
  illustrated 
  by 
  the 
  case 
  of 
  this 
  

   fly, 
  for 
  whenever 
  it 
  suddenly 
  disappears 
  from 
  a 
  given 
  locality, 
  this 
  is 
  

   usually 
  due 
  to 
  the 
  attacks 
  of 
  its 
  parasites, 
  and 
  especially 
  one 
  Chalcid 
  

   fly, 
  the 
  Semiotelhis 
  [Homoporus] 
  destructor, 
  first 
  described 
  by 
  Say. 
  

  

  This 
  is 
  a 
  hymenopterous 
  insect, 
  having 
  four 
  wings 
  and 
  belonging 
  to 
  

   the 
  same 
  order 
  of 
  insects 
  as 
  the 
  saw-flies, 
  four- 
  winged 
  gall-flies 
  (O^/wij^^), 
  

   the 
  larger 
  ichneumons, 
  and 
  the 
  wasps 
  and 
  bees. 
  It 
  is 
  a 
  member 
  of 
  the 
  

   family 
  Chalcididw, 
  As 
  stated 
  in 
  our 
  Guide 
  to-the 
  Study 
  of 
  Insects 
  , 
  this 
  is 
  

   a 
  group 
  of 
  great 
  extent, 
  the 
  species 
  being 
  of 
  small 
  sizej 
  they 
  are 
  often 
  

   of 
  shiny 
  colors, 
  as 
  the 
  name 
  of 
  the 
  principal 
  genus 
  implies, 
  being 
  either 
  

   bronze 
  or 
  metallic. 
  They 
  also 
  have 
  elbowed 
  antenutne 
  with 
  from 
  six 
  to 
  

   fourteen 
  joints, 
  and 
  the 
  wings 
  are 
  often 
  deficient 
  in 
  veins. 
  The 
  abdomen 
  

   is 
  usually 
  smaller, 
  and 
  composed 
  ordinarily 
  of 
  seven 
  rings 
  in 
  the 
  male, 
  

   and 
  of 
  six 
  in 
  the 
  female, 
  the 
  latter 
  often 
  having 
  a 
  short 
  but 
  visible 
  ovi- 
  

   positor, 
  a 
  horny 
  tube 
  consisting 
  of 
  three 
  pairs 
  of 
  stout 
  bristles 
  closely 
  

  

  