﻿225 
  

  

  This 
  substance 
  has 
  many 
  advantages 
  over 
  carbon 
  bisulphide, 
  since 
  

   it 
  is 
  not 
  inflammable, 
  can 
  be 
  used 
  at 
  all 
  times 
  of 
  the 
  year, 
  water 
  not 
  

   being 
  at 
  all 
  necessary, 
  and 
  has 
  no 
  ill 
  effects 
  on 
  neighbouring 
  plants. 
  

   When 
  done 
  thoroughly, 
  as 
  described, 
  the 
  results 
  are 
  said 
  to 
  be 
  perfect. 
  

  

  Headlee 
  (T. 
  J.) 
  & 
  Parker 
  (J. 
  B.). 
  The 
  Hessian 
  Fly.— 
  Kansas 
  State 
  

   Agric. 
  Expt. 
  Stn., 
  Manhattan, 
  Bull 
  188, 
  July 
  1913, 
  pp. 
  87-138, 
  

   15 
  figs. 
  [Reed. 
  28th 
  March 
  1914.] 
  

  

  The 
  Hessian 
  Fly 
  first 
  appeared 
  in 
  Long 
  Island 
  in 
  1779 
  and 
  has 
  spread 
  

   north, 
  south 
  and 
  west, 
  causing 
  serious 
  loss 
  in 
  most 
  of 
  the 
  wheat- 
  

   growing 
  regions 
  of 
  the 
  United 
  States. 
  Since 
  its 
  first 
  appearance 
  in 
  

   Kansas 
  the 
  fly 
  has 
  alternately 
  disappeared 
  and 
  reappeared, 
  since 
  

   unfavourable 
  weather 
  conditions 
  or 
  an 
  undue 
  abundance 
  of 
  natural 
  

   enemies 
  may 
  almost 
  eradicate 
  it. 
  The 
  egg 
  is 
  deposited 
  upon 
  the 
  upper 
  

   surface 
  of 
  the 
  leaf, 
  generally 
  on 
  wheat, 
  rye, 
  and 
  barley, 
  though 
  recent 
  

   evidence 
  shows 
  that 
  certain 
  wild 
  grasses, 
  as 
  Agropyron 
  smithii, 
  serve 
  

   as 
  well. 
  The 
  length 
  of 
  the 
  egg 
  stage 
  varies 
  from 
  two 
  to 
  ten 
  or 
  more 
  

   days. 
  An 
  individual 
  bred 
  in 
  an 
  insectary, 
  in 
  an 
  average 
  temperature 
  

   of 
  67° 
  F. 
  and 
  an 
  average 
  mean 
  relative 
  humidity 
  of 
  67 
  "2 
  per 
  cent, 
  

   required 
  60 
  days 
  to 
  pass 
  through 
  all 
  its 
  transformations, 
  of 
  which 
  26 
  

   days 
  were 
  occupied 
  in 
  the 
  period 
  from 
  hatching 
  to 
  the 
  formation 
  of 
  

   puparium. 
  The 
  length 
  of 
  the 
  hfe 
  of 
  the 
  adult 
  fly, 
  a 
  tiny 
  long-legged 
  

   gnat, 
  is 
  usually 
  limited 
  to 
  a 
  few 
  days. 
  The 
  number 
  of 
  broods 
  in 
  Kansas 
  

   varies 
  with 
  the 
  climatic 
  conditions. 
  In 
  1908, 
  the 
  summer 
  of 
  which 
  

   was 
  very 
  wet, 
  there 
  appear 
  to 
  have 
  been 
  two 
  main 
  broods 
  and 
  three 
  

   supplemental 
  broods. 
  The 
  main 
  spring 
  brood 
  emerged 
  during 
  March 
  

   and 
  April 
  ; 
  a 
  supplementary 
  spring 
  brood 
  emerged 
  between 
  7th 
  May 
  

   and 
  1st 
  June 
  ; 
  a 
  midsummer 
  brood 
  emerged 
  between 
  harvest 
  and 
  

   wheat 
  sow^ing 
  on 
  the 
  volunteer 
  wheat 
  ; 
  and 
  the 
  main 
  autumn 
  brood 
  

   of 
  adult 
  flies 
  emerged 
  between 
  22nd 
  September 
  and 
  28th 
  October. 
  

   None 
  of 
  these 
  produced 
  progeny 
  which 
  reached 
  the 
  adult 
  stage 
  before 
  

   winter. 
  From 
  the 
  15th 
  to 
  30th 
  October, 
  a 
  supplemental 
  autumn 
  

   brood 
  emerged. 
  Normally 
  the 
  midsummer 
  brood 
  might 
  be 
  almost 
  

   entirely 
  suppressed 
  and 
  no 
  supplemental 
  autumn 
  brood 
  developed. 
  

   Temperature 
  and 
  moisture 
  probably 
  exert 
  the 
  largest 
  mfluence 
  on 
  

   the 
  Hessian 
  fly. 
  The 
  low 
  temperature 
  of 
  winter 
  prolongs 
  the 
  life- 
  

   cycle 
  of 
  the 
  fly 
  from 
  30 
  to 
  60 
  days 
  to 
  6 
  months. 
  Gossard 
  and 
  Houser 
  

   showed 
  that 
  eggs 
  after 
  being 
  subjected 
  to 
  a 
  very 
  severe 
  frost 
  in 
  the 
  

   field 
  are 
  not 
  injured. 
  In 
  a 
  moist 
  atmosphere 
  eggs 
  withstood 
  107 
  •6°F. 
  

   easily 
  for 
  three 
  days. 
  Drought 
  is 
  dangerous 
  to 
  the 
  fly 
  and 
  plenty 
  of 
  

   atmospheric 
  moisture 
  is 
  favourable 
  to 
  it. 
  

  

  Osborn 
  records 
  for 
  America 
  six 
  species 
  of 
  insects 
  parasitic 
  on 
  the 
  

   Hessian 
  fly, 
  namely, 
  Merisns 
  destructor, 
  Say, 
  Homoporus 
  suhapterus, 
  

   Riley, 
  Ptero7nalus 
  p^d^^ij^^s^ 
  Forbes, 
  Eupelmus 
  allyni, 
  French, 
  Eyitodon 
  

   epigonus, 
  Walk., 
  Polygnotus 
  hiemalis, 
  Forbes, 
  and 
  Platygaster 
  herricJci, 
  

   Packard. 
  Tetrastichus 
  jyroductus, 
  Riley, 
  and 
  T. 
  carinatus, 
  Forbes, 
  

   are 
  parasites 
  attacking 
  the 
  primary 
  parasites 
  of 
  the 
  fly. 
  A 
  new 
  species 
  

   of 
  Sciara 
  and 
  a 
  wire-worm 
  were 
  found 
  to' 
  be 
  predaceous 
  enemies 
  of 
  the 
  

   Hessian 
  fly. 
  

  

  The 
  autumn 
  broods 
  of 
  maggots 
  attack 
  the 
  wheat 
  plants 
  when 
  they 
  

   are 
  young 
  and 
  the 
  infested 
  stalks 
  are 
  always 
  stunted 
  and 
  frequently 
  

   killed, 
  though 
  " 
  tillers 
  " 
  may 
  grow 
  out 
  from 
  below 
  the 
  point 
  of 
  injury. 
  

  

  