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  the 
  epidermis, 
  through 
  which 
  the 
  adult 
  eventually 
  emerges. 
  This 
  

   membrane 
  is 
  easily 
  visible 
  on 
  the 
  stem, 
  when 
  above 
  the 
  soil. 
  It 
  is 
  

   grey 
  or 
  brown 
  in 
  colour, 
  from 
  2J 
  to 
  10 
  mm. 
  long 
  and 
  2 
  to 
  4 
  mm. 
  wide. 
  

   Having 
  made 
  these 
  preparations 
  the 
  larva 
  descends 
  again 
  and 
  generally 
  

   pupates 
  head 
  upwards. 
  The 
  depth 
  of 
  the 
  galleries, 
  the 
  point 
  where 
  

   pupation 
  takes 
  place 
  and 
  the 
  position 
  of 
  the 
  exit 
  aperture 
  are 
  most 
  

   important 
  factors 
  in 
  control. 
  The 
  author 
  gives 
  6 
  detailed 
  tables 
  of 
  

   the 
  results 
  of 
  his 
  observations. 
  The 
  distance 
  between 
  the 
  orifice 
  of 
  

   the 
  gallery 
  and 
  the 
  point 
  where 
  the 
  pupa 
  is 
  fixed 
  varies 
  between 
  IJ 
  

   and 
  4J 
  inches 
  ; 
  pupation 
  generally 
  takes 
  place 
  at 
  from 
  2 
  to 
  5 
  inches 
  

   below 
  the 
  surface 
  of 
  the 
  soil, 
  and 
  very 
  rarely 
  a 
  little 
  above 
  the 
  level 
  

   of 
  the 
  soil. 
  Thin 
  asparagus 
  stems 
  are 
  usually 
  immune 
  ; 
  one-year-old 
  

   plants 
  are 
  therefore 
  seldom 
  attacked, 
  those 
  of 
  two 
  years' 
  growth 
  

   suffering 
  most. 
  In 
  1904 
  and 
  1905, 
  two-year-old 
  asparagus 
  plantations 
  

   at 
  Epinay 
  were 
  destroyed 
  to 
  the 
  extent 
  of 
  one-half 
  or 
  even 
  three- 
  

   fifths, 
  and 
  many 
  growers 
  abandoned 
  its 
  cultivation. 
  Heavy 
  or 
  pro- 
  

   longed 
  rains 
  cause 
  many 
  adult 
  flies 
  to 
  disappear, 
  as 
  they 
  can 
  get 
  no 
  

   adequate 
  shelter. 
  Cold 
  seems 
  fatal 
  to 
  the 
  eggs, 
  since 
  on 
  the 
  16th 
  May 
  

   1909 
  the 
  author 
  found 
  the 
  embryos 
  dead 
  in 
  eggs 
  from 
  heads 
  collected 
  

   that 
  same 
  morning 
  at 
  Argenteuil, 
  slight 
  frosts 
  having 
  occurred 
  during 
  

   the 
  preceding 
  nights. 
  

  

  In 
  1903, 
  Giard 
  reported 
  the 
  presence 
  of 
  a 
  Geophilid 
  in 
  stems 
  attacked 
  

   by 
  Platyparea 
  larvae, 
  but 
  the 
  author 
  has 
  never 
  observed 
  the 
  latter 
  

   to 
  be 
  attacked. 
  In 
  the 
  Argenteuil 
  district, 
  parasites 
  appear 
  to 
  be 
  rare. 
  

   The 
  author 
  was 
  able 
  to 
  breed 
  only 
  one, 
  a 
  Braconid, 
  and 
  then 
  only 
  

   obtained 
  two 
  females, 
  which 
  emerged 
  in 
  April 
  1911. 
  This 
  Br 
  aeon 
  

   is 
  nearly 
  allied 
  to 
  B. 
  satanas, 
  Wesmael, 
  and 
  may 
  be 
  a 
  form 
  of 
  it. 
  When 
  

   the 
  Platyparea 
  larvae 
  are 
  too 
  numerous 
  in 
  a 
  given 
  stem, 
  food 
  fails 
  

   them 
  and 
  they 
  devour 
  one 
  another 
  ; 
  they 
  also 
  attack 
  each 
  other 
  when 
  

   they 
  meet 
  in 
  the 
  mines, 
  even 
  when 
  food 
  is 
  abundant. 
  

  

  The 
  burning 
  of 
  dead 
  stems 
  in 
  winter, 
  which 
  was 
  formerly 
  prescribed, 
  

   does 
  not 
  destroy 
  all 
  the 
  pupae, 
  because 
  the 
  rapid 
  decomposition 
  of 
  

   the 
  thinner 
  heads 
  allows 
  many 
  pupae 
  to 
  subsist 
  in 
  the 
  soil 
  where 
  

   winter 
  treatment 
  cannot 
  reach 
  them. 
  The 
  only 
  suitable 
  moment 
  for 
  

   destroying 
  the 
  insects 
  is 
  when 
  the 
  heads 
  show 
  the 
  first 
  signs 
  of 
  injury. 
  

   They 
  should 
  then 
  be 
  detached 
  from 
  the 
  root, 
  rather 
  than 
  cut, 
  since 
  

   the 
  larva 
  may 
  descend 
  as 
  far 
  as 
  the 
  point 
  where 
  the 
  stem 
  is 
  inserted 
  

   into 
  the 
  root. 
  The 
  decomposition 
  which 
  some 
  stems 
  undergo 
  makes 
  

   it 
  impossible 
  to 
  pull 
  them 
  up, 
  and 
  the 
  pupae 
  underground 
  escape 
  

   destruction, 
  though 
  this 
  might 
  be 
  obviated 
  if 
  the 
  injured 
  stems 
  were 
  

   removed 
  at 
  the 
  end 
  of 
  the 
  season 
  when 
  they 
  are 
  cut 
  about 
  4 
  to 
  8 
  inches 
  

   above 
  the 
  soil. 
  Any 
  injury 
  is 
  then 
  clearly 
  visible, 
  as 
  the 
  galleries 
  

   appear 
  as 
  circular 
  holes 
  about 
  2 
  millimetres 
  in 
  diameter. 
  The 
  burning 
  

   of 
  the 
  bases 
  of 
  the 
  stems 
  (cotons) 
  as 
  now 
  practised 
  in 
  the 
  field 
  is 
  often 
  

   incomplete, 
  and 
  the 
  author 
  has 
  frequently 
  picked 
  up 
  stems 
  carbonised 
  

   at 
  one 
  end 
  and 
  containing 
  living 
  pupae 
  at 
  the 
  other. 
  Better 
  results 
  

   would 
  be 
  obtained 
  if 
  the 
  growers 
  were 
  to 
  bring 
  the 
  " 
  cotons 
  " 
  to 
  a 
  

   specified 
  shed 
  where 
  they 
  might 
  be 
  dried 
  and 
  completely 
  burnt. 
  

   Abandoned 
  asparagus 
  beds 
  constitute 
  a 
  centre 
  of 
  infection 
  and 
  should 
  

   be 
  cleared. 
  The 
  author 
  gives 
  a 
  map 
  and 
  list 
  of 
  infected 
  localities. 
  

   The 
  fly 
  prefers 
  protected 
  slopes 
  wdth 
  a 
  south 
  aspect. 
  A 
  bibliography 
  

   of 
  15 
  works 
  (1776-1 
  ^09") 
  concbides 
  the 
  paper. 
  

  

  