﻿the 
  Hessian 
  Fly. 
  345 
  

  

  On 
  the 
  ninth 
  day 
  the 
  eyes 
  were 
  much 
  darker, 
  and 
  the 
  

   tips 
  of 
  the 
  feet 
  or 
  claws 
  visible, 
  and 
  the 
  second 
  pair 
  of 
  

   legs 
  traced 
  under 
  the 
  wings 
  ; 
  thorax 
  much 
  darker, 
  inclined 
  

   to 
  brown. 
  

  

  The 
  next 
  day, 
  wings 
  almost 
  black, 
  and 
  thorax 
  very 
  

   dark 
  colour, 
  but 
  the 
  eyes 
  were 
  not 
  distinguishable 
  from 
  

   the 
  other 
  parts. 
  In 
  the 
  evening, 
  when 
  I 
  examined 
  the 
  

   pupa 
  with 
  side 
  illumination, 
  I 
  could 
  see 
  the 
  hairs 
  on 
  the 
  

   abdomen, 
  and 
  mark 
  the 
  strong 
  pulsations 
  ; 
  the 
  abdomen 
  

   was 
  much 
  swollen, 
  and 
  the 
  legs 
  projected 
  and 
  stood 
  clean 
  

   away 
  from 
  the 
  ventral 
  surface. 
  

  

  At 
  eleven 
  days 
  old 
  the 
  dorsal 
  and 
  ventral 
  markings 
  

   clearly 
  seen, 
  the 
  ventral 
  segments 
  of 
  a 
  blood-red 
  colour, 
  

   with 
  scales 
  on 
  back 
  very 
  plain 
  and 
  dark 
  ; 
  at 
  night, 
  when 
  

   examining 
  this 
  and 
  other 
  pupae, 
  I 
  noticed 
  that 
  they 
  were 
  

   very 
  susceptible 
  to 
  the 
  light 
  from 
  the 
  side 
  reflector, 
  all 
  

   twisting 
  and 
  twirling 
  about 
  directly 
  it 
  was 
  concentrated 
  

   upon 
  them. 
  At 
  9 
  p.m. 
  the 
  skin 
  of 
  the 
  abdomen 
  appeared 
  

   silvery, 
  as 
  though 
  the 
  internal 
  moisture 
  was 
  absorbed. 
  

  

  On 
  the 
  twelfth 
  day, 
  at 
  5 
  a.m., 
  the 
  pupa 
  was 
  quiet, 
  with 
  

   the 
  exception 
  of 
  a 
  slight 
  quivering 
  of 
  the 
  tail 
  ; 
  but 
  on 
  the 
  

   following 
  day, 
  at 
  4 
  a.m., 
  it 
  commenced 
  writhing 
  about 
  

   for 
  a 
  quarter 
  of 
  an 
  hour, 
  then 
  a 
  rest, 
  followed 
  at 
  4.45 
  by 
  

   tremendous 
  muscular 
  efforts, 
  and 
  at 
  last 
  it 
  succeeded 
  in 
  

   bursting 
  its 
  shell, 
  the 
  female 
  fly 
  gradually 
  working 
  its 
  

   way 
  out. 
  From 
  the 
  number 
  of 
  larvae 
  I 
  have 
  watched 
  

   change 
  to 
  pupae, 
  and 
  then 
  on 
  until 
  the 
  flies 
  emerged, 
  

   I 
  find 
  the 
  time 
  varies 
  from 
  twelve 
  to 
  thirteen 
  days 
  for 
  

   both 
  sexes. 
  One 
  peculiarity 
  I 
  noted 
  was 
  the 
  time 
  at 
  

   which 
  the 
  larvae 
  changed 
  to 
  pupae 
  — 
  in 
  nearly 
  every 
  

   instance 
  between 
  9 
  p.m. 
  and 
  3 
  a.m. 
  

  

  On 
  August 
  3rd, 
  1888, 
  I 
  bred 
  a 
  male 
  Hessian 
  Fly 
  from 
  

   eggs 
  laid 
  June 
  2nd, 
  giving 
  sixty 
  -three 
  days 
  for 
  the 
  entire 
  

   transformation. 
  

  

  For 
  the 
  sake 
  of 
  convenience, 
  I 
  placed 
  a 
  certain 
  number 
  

   of 
  free 
  puparia 
  in 
  flower-pots 
  filled 
  up 
  to 
  within 
  three- 
  

   quarters 
  of 
  an 
  inch 
  of 
  the 
  top 
  with 
  damp 
  sand, 
  covered 
  

   with 
  white 
  blotting-paper. 
  On 
  this 
  I 
  laid 
  the 
  puparia 
  in 
  

   rows, 
  examining 
  them 
  every 
  morning 
  to 
  see 
  at 
  what 
  time 
  

   the 
  flies 
  emerged 
  ; 
  after 
  many 
  mornings' 
  close 
  watching 
  

   with 
  a 
  hand-magnifier, 
  I 
  found 
  some 
  just 
  expanding 
  their 
  

   wings 
  at 
  3.50 
  a.m., 
  and, 
  though 
  I 
  have 
  watched 
  as 
  soon 
  

   as 
  daylight 
  appeared, 
  I 
  never 
  found 
  any 
  out 
  at 
  an 
  earlier 
  

   hour; 
  the 
  greater 
  number 
  came 
  out 
  between 
  5 
  and 
  

   7 
  a.m., 
  and 
  others 
  in 
  the 
  afternoon 
  up 
  to 
  7.30 
  p.m. 
  

  

  