﻿— 
  6i 
  — 
  

  

  to 
  interfere 
  with 
  each 
  other's 
  food 
  supply, 
  some 
  of 
  them 
  may 
  leave 
  their 
  

   native 
  mines 
  and 
  form 
  others 
  elsewhere. 
  The 
  leaf-miners 
  observed 
  by 
  

   Dr. 
  Lintner 
  usually 
  entered 
  the 
  earth 
  for 
  pupation, 
  although 
  a 
  few 
  

   formed 
  their 
  puparia 
  between 
  the 
  leaves. 
  From 
  existing 
  accounts 
  it 
  

   appears 
  that 
  the 
  species 
  hibernate 
  in 
  the 
  puparia, 
  from 
  which 
  the 
  flies 
  

   emerge 
  in 
  April 
  and 
  May. 
  The 
  work 
  of 
  the 
  larvae 
  has 
  been 
  seen 
  in 
  the 
  

   field 
  from 
  the 
  middle 
  of 
  May 
  until 
  November 
  20. 
  In 
  Howard's 
  breed- 
  

   ing 
  experiments 
  the 
  life 
  cycle 
  of 
  a 
  generation 
  was 
  about 
  a 
  month 
  in 
  

   length, 
  and 
  there 
  are 
  evidently 
  several 
  broods 
  in 
  a 
  season, 
  six 
  or 
  seven 
  

   in 
  New 
  York, 
  according 
  to 
  Sirrine's 
  opinion. 
  The 
  great 
  variation 
  in 
  

   the 
  numbers 
  of 
  these 
  insects 
  in 
  different 
  years 
  is 
  probably 
  to 
  be 
  ex- 
  

   plained, 
  in 
  part 
  at 
  least, 
  by 
  the 
  destruction 
  of 
  their 
  eggs 
  and 
  larvae 
  by 
  

   other 
  insects. 
  Most 
  of 
  the 
  eggs 
  examined 
  by 
  Lintner 
  in 
  September, 
  

   1881, 
  had 
  been 
  destroyed, 
  apparently 
  by 
  some 
  insect 
  which 
  punctured 
  

   them 
  and 
  fed 
  upon 
  their 
  contents. 
  A 
  common 
  predaceous 
  insect, 
  

   Coriscus 
  ferus, 
  was 
  observed 
  by 
  Sirrine 
  apparently 
  puncturing 
  the 
  larvae 
  

   from 
  the 
  outside 
  as 
  they 
  lay 
  in 
  the 
  mines. 
  

  

  The 
  following 
  general 
  description 
  of 
  Pegomyia 
  vicina 
  in 
  its 
  several 
  

   stages, 
  given 
  by 
  Mr. 
  Sirrine, 
  will 
  serve 
  for 
  the 
  identification 
  of 
  these 
  

   insects. 
  

  

  "The 
  eggs 
  are 
  white, 
  about 
  .03 
  of 
  an 
  inch 
  in 
  length, 
  delicately 
  

   reticulated 
  and 
  nearly 
  cylindrical 
  in 
  shape. 
  The 
  white 
  reticulated 
  por- 
  

   tion 
  of 
  the 
  egg 
  is 
  an 
  outer 
  covering, 
  and 
  is 
  easily 
  removed 
  in 
  little 
  

   scale-like 
  particles. 
  When 
  the 
  eggs 
  are 
  deposited 
  this 
  covering 
  is 
  

   apparently 
  viscid 
  and 
  aids 
  in 
  attaching 
  them 
  to 
  the 
  leaf. 
  Beneath 
  this 
  

   reticulated 
  covering 
  is 
  a 
  semi-transparent 
  membrane. 
  

  

  "The 
  maggot 
  or 
  larva 
  is 
  about 
  five-sixteenths 
  of 
  an 
  inch 
  long 
  when 
  

   full 
  grown, 
  larger 
  at 
  the 
  posterior 
  than 
  at 
  the 
  anterior 
  end. 
  When 
  first 
  

   taken 
  from 
  the 
  leaf 
  they 
  have 
  a 
  white, 
  glassy 
  appearance. 
  In 
  the 
  

   posterior 
  half 
  of 
  the 
  body 
  the 
  green 
  contents 
  of 
  the 
  intestine 
  show 
  quite 
  

   distinctly, 
  while 
  the 
  black, 
  hook-like 
  jaws, 
  or 
  what 
  answers 
  for 
  jaws, 
  

   can 
  be 
  seen 
  as 
  a 
  curved 
  line 
  at 
  the 
  anterior 
  end. 
  

  

  " 
  The 
  puparium, 
  or 
  resting 
  stage, 
  is 
  about 
  .21 
  of 
  an 
  inch' 
  long, 
  

   chestnut-brown 
  in 
  color 
  when 
  formed, 
  but 
  soon 
  changing 
  to 
  a 
  dark 
  

   brown 
  and 
  difficult 
  to 
  distinguish 
  from 
  the 
  surrounding 
  soil. 
  

  

  " 
  The 
  flies 
  are 
  quite 
  variable 
  in 
  size. 
  They 
  usually 
  carry 
  the 
  body 
  

   in 
  a 
  slightly 
  curved 
  position. 
  The 
  front 
  of 
  the 
  head 
  is 
  silvery 
  white 
  

   with 
  a 
  reddish 
  brown 
  line 
  extending 
  vertically 
  through 
  the 
  center. 
  The 
  

   females 
  are 
  of 
  an 
  olivaceous 
  ash 
  color, 
  and 
  can 
  be 
  distinguished 
  from 
  

   the 
  males 
  by 
  the 
  following 
  characters: 
  The 
  eyes 
  are 
  smaller 
  and 
  placed 
  

   further 
  apart 
  than 
  in 
  the 
  male. 
  The 
  legs, 
  excepting 
  the 
  tarsi, 
  are 
  yellow 
  

   or 
  reddish 
  yellow. 
  The 
  body 
  is 
  not 
  as 
  hairy 
  as 
  in 
  the 
  males, 
  nor 
  are 
  

   the 
  hairs 
  as 
  long, 
  except 
  at 
  the 
  end 
  of 
  the 
  abdomen 
  where 
  there 
  is 
  

   a 
  distinct 
  tuft 
  of 
  long 
  hairs. 
  The 
  males 
  are 
  darker 
  colored 
  than 
  the 
  

  

  