﻿176 
  REPORT 
  UNITED 
  STATES 
  ENTOMOLOGICAL 
  COMMISSION. 
  

  

  The 
  flies 
  issue 
  in 
  May, 
  and 
  we 
  have 
  bred 
  the 
  same 
  species 
  from 
  cocoons 
  

  

  from 
  Canker- 
  Worm 
  larvae 
  (doubtless 
  vernata)^ 
  received 
  from 
  Mr. 
  J. 
  

  

  Pettit, 
  of 
  Grimsby, 
  Canada. 
  About 
  10 
  per 
  cent, 
  of 
  the 
  worms 
  which 
  we 
  

   have 
  endeavored 
  to 
  breed 
  have 
  been 
  destroyed 
  by 
  

   this 
  parasite. 
  Harris 
  mentions 
  the 
  larva 
  of 
  another 
  

   four- 
  winged 
  fly 
  (probably 
  Microgaster), 
  which 
  preys 
  

   on 
  the 
  fatty 
  substance 
  of 
  the 
  Canker 
  Worm, 
  and 
  

   weakens 
  it 
  so 
  much 
  that 
  it. 
  is 
  unable 
  to 
  go 
  through 
  

   its 
  future 
  transformations, 
  and 
  that 
  of 
  a 
  two- 
  winged 
  

   fly 
  belonging 
  to 
  the 
  genus 
  TacMna, 
  which 
  also 
  

   infests 
  the 
  worms, 
  destroying 
  about 
  one-third 
  of 
  

  

  ^ 
  ^ 
  ^r 
  sr. 
  them 
  in 
  Massachusetts. 
  He 
  says 
  he 
  has 
  seen 
  the 
  

  

  Fig. 
  2. 
  — 
  Nothrus 
  ovivorus 
  "^ 
  

  

  (after 
  Packard). 
  former 
  of 
  thcsc 
  flics 
  sting 
  scvcral 
  Canker 
  Worms 
  in 
  

  

  succession, 
  and 
  swarms 
  of 
  them 
  may 
  be 
  observed 
  around 
  the 
  tree 
  as 
  

   long 
  as 
  the 
  Canker 
  Worms 
  remain. 
  Their 
  services, 
  therefore, 
  are 
  doubt- 
  

   less 
  very 
  considerable, 
  but 
  it 
  is 
  impossible 
  to 
  say, 
  from 
  present 
  informa- 
  

   tion, 
  upon 
  which 
  species 
  they 
  prey, 
  or 
  whether 
  upon 
  both. 
  We 
  also 
  

   received 
  from 
  Mr. 
  Pettit, 
  in 
  addition 
  to 
  the 
  Microgaster 
  paleacritce 
  which 
  

   he 
  found 
  upon 
  Canker 
  Worms, 
  at 
  Grimsby, 
  some 
  net-work 
  cocoons, 
  

   inclosing 
  each 
  of 
  them 
  a 
  parasitic 
  larva, 
  which 
  had 
  preyed 
  upon 
  the 
  

   Canker 
  Worm. 
  Each 
  dead 
  Canker 
  Worm 
  was 
  secured 
  to 
  the 
  leaf 
  

   upon 
  which 
  it 
  rested 
  by 
  one 
  of 
  these 
  cocoons, 
  which 
  seemed 
  at 
  first 
  

   sight 
  to 
  be 
  a 
  cluster 
  of 
  eggs 
  attached 
  to 
  the 
  body 
  of 
  the 
  Canker 
  Worm.^^ 
  

   From 
  subsequent 
  exx)erience 
  with 
  the 
  genus 
  we 
  have 
  little 
  doubt 
  but 
  

   that 
  these 
  were 
  larvae 
  of 
  Miplectrus. 
  

  

  The 
  maggots 
  of 
  the 
  Tachina 
  parasite, 
  mentioned 
  by 
  Harris, 
  live 
  singly 
  

   within 
  the 
  bodies 
  of 
  the 
  Canker 
  Worms, 
  till 
  the 
  latter 
  die 
  from 
  weak- 
  

   ness 
  j 
  after 
  which 
  they 
  undergo 
  a 
  change, 
  and 
  finally 
  come 
  out 
  of 
  the 
  

   bodies 
  of 
  their 
  victims 
  in 
  their 
  i^erfect 
  form. 
  

  

  There 
  is 
  also 
  a 
  very 
  minute 
  and 
  undescribed 
  species 
  of 
  Platygaster 
  

  

  (so 
  called), 
  first 
  discovered 
  by 
  Mr. 
  E. 
  C. 
  Herrick, 
  of 
  New 
  Haven, 
  Conn., 
  

  

  which 
  pierces 
  the 
  egg 
  of 
  the 
  Fall 
  species, 
  and 
  drops 
  one 
  of 
  her 
  own 
  eggs 
  

  

  into 
  it, 
  from 
  which 
  in 
  due 
  time 
  the 
  perfect 
  fly 
  develops. 
  Sometimes 
  

  

  every 
  Canker 
  Worm 
  egg 
  in 
  a 
  cluster 
  will 
  be 
  found 
  to 
  have 
  been 
  thus 
  

  

  punctured 
  and 
  seeded 
  for 
  a 
  future 
  harvest 
  of 
  the 
  Flatygaster, 
  The 
  

  

  young 
  of 
  this 
  Flatygaster 
  is 
  an 
  exceedingly 
  minute 
  maggot, 
  hatched 
  

  

  ^^^^*+hiii 
  the 
  Canker 
  Worm 
  egg, 
  the 
  shell 
  of 
  which, 
  though 
  only 
  one- 
  

  

  ^^f 
  y.'^^th 
  of 
  an 
  inch 
  long, 
  serves 
  for 
  its 
  habitation, 
  and 
  the 
  contents 
  

  

  .. 
  'fo^^d, 
  till 
  it 
  is 
  fully 
  grown; 
  after 
  which 
  it 
  becomes 
  a 
  chrysalis 
  

  

  • 
  v.* 
  tbe 
  Sc*^™^ 
  shell, 
  and 
  in 
  due 
  time 
  comes 
  out 
  a 
  Flatygaster 
  fly, 
  like 
  

  

  ^^ 
  put 
  '!?^is 
  last 
  transformation 
  Mr. 
  Herrick 
  found 
  to 
  take 
  place 
  

  

  ^ 
  , 
  ^^Q 
  end 
  of 
  June, 
  from 
  eggs 
  laid 
  in 
  November 
  of 
  the 
  year 
  before 
  j 
  

  

  ri 
  "hp 
  thinks 
  ti^at 
  the 
  flies 
  continue 
  alive 
  through 
  the 
  summer, 
  till 
  the 
  

  

  ^^^ 
  ranee 
  of 
  tb.^ 
  Canker 
  Worm 
  moths 
  in 
  the 
  autumn 
  affords 
  them 
  the 
  

  

  ^ 
  tanity 
  of 
  l^y^S 
  their 
  eggs 
  for 
  another 
  brood. 
  As 
  these 
  little 
  

  

  soAmer. 
  Entomologist, 
  v. 
  1, 
  p. 
  246. 
  

  

  