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  OBSERVATIONS 
  ON 
  THE 
  OVIPOSITION 
  OF 
  THE 
  HOUSE-FLY, 
  

   MUSCA 
  DOMESTICA, 
  L., 
  IN 
  PANAMA.* 
  

  

  By 
  L. 
  H. 
  Dunn, 
  

   Entomologist, 
  Board 
  of 
  Health 
  Laboratory, 
  Ancon, 
  Canal 
  Zone. 
  

  

  During 
  the 
  past 
  twenty-five 
  years 
  and 
  more 
  the 
  house-fly, 
  Mitsca 
  domestica, 
  L., 
  

   has 
  received 
  much 
  attention 
  from 
  entomologists, 
  medical 
  men, 
  sanitarians 
  and 
  other 
  

   investigators, 
  and 
  many 
  observations 
  on 
  the 
  life-history, 
  habits, 
  etc., 
  of 
  this 
  fly 
  

   have 
  been 
  made 
  by 
  individuals 
  in 
  different 
  parts 
  of 
  the 
  world. 
  As 
  a 
  result 
  of 
  the 
  

   investigations 
  carried 
  out 
  during 
  this 
  period 
  much 
  information 
  has 
  been 
  accumulated 
  

   regarding 
  the 
  biology 
  of 
  this 
  dangerous 
  nuisance 
  to 
  mankind. 
  However, 
  notwith- 
  

   standing 
  all 
  these 
  observations 
  and 
  the 
  great 
  amount 
  of 
  knowledge 
  that 
  has 
  been 
  

   gained, 
  there 
  are 
  a 
  few 
  points 
  that 
  have 
  remained 
  more 
  or 
  less 
  indefinite. 
  One 
  of 
  

   these 
  is 
  concerning 
  the 
  oviposition 
  of 
  the 
  female 
  fly 
  ; 
  the 
  number 
  of 
  eggs 
  deposited 
  

   during 
  her 
  life-period 
  and 
  the 
  time 
  elapsing 
  between 
  depositions. 
  

  

  According 
  to 
  Newstead.f 
  " 
  The 
  number 
  of 
  eggs 
  laid 
  by 
  a 
  single 
  fly 
  averages 
  

   from 
  120 
  to 
  140. 
  More 
  than 
  one 
  batch 
  may 
  be 
  laid 
  during 
  the 
  life 
  of 
  the 
  fly, 
  but 
  

   this 
  question 
  has 
  not 
  been 
  definitely 
  settled." 
  

  

  Howard^ 
  states, 
  " 
  Each 
  female 
  fly 
  lays 
  on 
  the 
  average 
  120 
  eggs, 
  or 
  perhaps 
  more, 
  

   at 
  a 
  time 
  and 
  may 
  lay 
  several 
  times. 
  Forbes' 
  assistants 
  in 
  Illinois 
  found 
  that 
  eggs 
  

   1rom 
  a 
  single 
  fly 
  vary 
  from 
  120 
  to 
  150 
  in 
  each 
  deposit, 
  and 
  that 
  as 
  many 
  as 
  four 
  

   deposits 
  may 
  be 
  made, 
  or, 
  say, 
  600 
  eggs 
  by 
  a 
  single 
  fly 
  {in 
  lilt.). 
  One 
  hundred 
  and 
  

   twenty 
  was 
  the 
  number 
  observed 
  by 
  the 
  writer 
  to 
  be 
  the 
  average 
  number, 
  but 
  

   Dr. 
  Hewitt 
  has 
  counted 
  as 
  many 
  as 
  150." 
  

  

  Hewitt§ 
  writes, 
  " 
  From 
  actual 
  counts 
  of 
  eggs 
  in 
  the 
  ovaries 
  of 
  dissected 
  flies 
  and 
  

   of 
  batches 
  which 
  have 
  been 
  deposited, 
  I 
  found 
  the 
  number 
  varied 
  from 
  100 
  to 
  150, 
  

   the 
  usual 
  number 
  being 
  120. 
  This 
  number 
  is 
  confirmed 
  by 
  other 
  observers. 
  During 
  

   its 
  lifetime 
  as 
  many 
  as 
  four 
  batches 
  of 
  eggs 
  may 
  be 
  laid, 
  as 
  shown 
  by 
  actual 
  obser- 
  

   vations, 
  by 
  the 
  same 
  fly, 
  and 
  a 
  careful 
  study 
  of 
  the 
  ovaries 
  of 
  a 
  large 
  number 
  of 
  female 
  

   flies 
  has 
  led 
  me 
  to 
  believe 
  that 
  five 
  or 
  even 
  six 
  batches 
  of 
  eggs 
  may 
  be 
  deposited." 
  

  

  Bishopp, 
  Dove 
  and 
  Parman|| 
  remark, 
  " 
  Dr. 
  A. 
  Griffith, 
  reporting 
  on 
  experiments 
  

   conducted 
  by 
  him 
  in 
  England, 
  says 
  : 
  ' 
  After 
  ten 
  days 
  the 
  mother 
  fly 
  can 
  lay 
  a 
  new 
  

  

  * 
  These 
  observations 
  were 
  carried 
  out 
  in 
  1918, 
  but 
  owing 
  to 
  the 
  writer 
  entering 
  the 
  military 
  

   service 
  and 
  leaving 
  the 
  Isthmus 
  this 
  article 
  was 
  not 
  prepared 
  for 
  publication 
  until 
  his 
  recent 
  

   return 
  to 
  the 
  Isthmus. 
  

  

  t 
  Newstead, 
  Robert, 
  " 
  On 
  the 
  Habits, 
  Life-cycle 
  and 
  Breeding 
  Places 
  of 
  the 
  Common 
  House- 
  

   fly 
  (Musca 
  domestica, 
  Linn.)." 
  — 
  Annals 
  of 
  Tropical 
  Medicine 
  and 
  Parasitology, 
  i, 
  p. 
  513, 
  Feb. 
  1908. 
  

  

  t 
  Howard, 
  L. 
  O., 
  " 
  The 
  House 
  Flv, 
  Disease 
  Carrier," 
  p. 
  18, 
  1911. 
  Fred 
  A. 
  Stokes 
  Co 
  New 
  

   York. 
  

  

  § 
  Hewitt, 
  C. 
  Gordon, 
  " 
  The 
  House-Fly," 
  p. 
  100, 
  1914. 
  The 
  University 
  Press, 
  Manchester, 
  

   England. 
  

  

  || 
  Bishopp, 
  F. 
  C, 
  Dove, 
  W. 
  E., 
  and 
  Parman, 
  D. 
  C. 
  " 
  Notes 
  on 
  Certain 
  Points 
  of 
  Economic 
  

   Importance 
  in 
  the 
  Biology 
  of 
  the 
  House 
  Fly." 
  — 
  Journal 
  of 
  Economic 
  Entomology, 
  viii 
  1 
  p 
  60 
  

   Feb. 
  1915. 
  

  

  