﻿PACKARD.] 
  POTATO-INSECTS. 
  737 
  

  

  there 
  is 
  a 
  little 
  fleshy 
  horn 
  on 
  each 
  side 
  ; 
  on 
  the 
  following 
  segment 
  is 
  a 
  

   spiracle 
  on 
  either 
  side, 
  surrounded 
  by 
  several 
  stout 
  short 
  rays 
  ; 
  the 
  two 
  

   next 
  segments 
  have 
  tubercles 
  on 
  the 
  back 
  ; 
  the 
  remainder 
  have 
  a 
  

   double 
  series 
  down 
  the 
  center, 
  producing 
  bristles, 
  with 
  a 
  double 
  row 
  

   on 
  each 
  and 
  eight 
  of 
  the 
  segments 
  have 
  a 
  pair 
  of 
  short 
  spines 
  

   each 
  beneath, 
  which 
  enable 
  it 
  to 
  walk 
  ; 
  the 
  apex 
  is 
  armed 
  with 
  six 
  

   long 
  bristles 
  a 
  little 
  spiny 
  at 
  the 
  base, 
  but 
  most 
  of 
  the 
  others 
  are 
  

   naked, 
  or 
  with 
  the 
  slightest 
  appearance 
  of 
  pubescence 
  or 
  little 
  spines 
  

   at 
  the 
  base 
  ; 
  on 
  the 
  apical 
  segment 
  are 
  two 
  spiracular 
  tubes. 
  The 
  pupa 
  

   being 
  formed 
  within 
  the 
  indurated 
  skin 
  of 
  the 
  larvae, 
  it 
  varies 
  from 
  it 
  

   only 
  in 
  being 
  more 
  convex 
  above, 
  and 
  the 
  fly 
  escapes 
  by 
  a 
  lateral 
  open- 
  

   ing 
  in 
  the 
  thorax. 
  

  

  " 
  Tbese 
  larvse 
  and 
  purpae 
  I 
  find 
  occasionally 
  in 
  my 
  garden 
  where 
  cab- 
  

   bages 
  have 
  long 
  occupied 
  the 
  ground, 
  and 
  Dr. 
  Harris 
  remarks 
  that 
  the 
  

   hairy 
  maggots 
  of 
  Anthomyia 
  cunicularis, 
  or 
  an 
  allied 
  species, 
  live 
  in 
  rot- 
  

   ten 
  turnips 
  ; 
  they 
  also 
  abound 
  in 
  i^rivies, 
  and 
  the 
  purpae-cases 
  are 
  found 
  

   in 
  multitudes 
  nnder 
  boards. 
  

  

  " 
  From 
  the 
  large 
  quantities 
  of 
  these 
  maggots 
  which 
  have 
  been 
  ejected 
  

   from 
  the 
  human 
  stomach 
  and 
  intestines, 
  accompanied 
  by 
  the 
  most 
  dis- 
  

   tr 
  'ssing 
  s.vmptoms, 
  I 
  am 
  led 
  to 
  conclude 
  from 
  their 
  economy 
  that 
  the 
  

   eggs 
  or 
  larvse 
  are 
  conveyed 
  into 
  the 
  stomach 
  in 
  badly 
  or 
  half 
  cooked 
  

   vegetables, 
  for 
  it 
  is 
  evident 
  they 
  subsist 
  upon 
  decomposing 
  vegetables 
  

   and 
  excrementitious 
  substances, 
  and 
  I 
  have 
  found 
  similar 
  but 
  very 
  small 
  

   larvse 
  on 
  cabbage-leaves 
  in 
  October. 
  It 
  is, 
  therefore, 
  very 
  probable 
  

   that, 
  under 
  certain 
  morbid 
  conditions 
  of 
  the 
  constitution, 
  they 
  are 
  able 
  

   to 
  live 
  in 
  the 
  human 
  body 
  until 
  they 
  have 
  arrived 
  at 
  their 
  full 
  growth, 
  

   when 
  they 
  are 
  necessarily 
  ejected 
  to 
  become 
  pupsB, 
  and 
  after 
  a 
  short 
  

   time 
  to 
  be 
  transformed 
  into 
  flies. 
  It 
  is 
  not 
  a 
  little 
  remarkable 
  that 
  the 
  

   maggots 
  of 
  Musca 
  stabulans 
  should 
  have 
  been 
  also 
  voided 
  from 
  the 
  in- 
  

   testines, 
  and 
  that 
  fact 
  tends 
  to 
  substantiate 
  the 
  view 
  I 
  have 
  taken 
  of 
  

   the 
  subject 
  and 
  the 
  cause 
  of 
  their 
  presence 
  in 
  the 
  human 
  system, 
  foi? 
  

   that 
  is 
  the 
  other 
  species 
  of 
  large 
  fly 
  which 
  I 
  bred 
  from 
  maggots 
  gen- 
  

   erated 
  in 
  the 
  same 
  potato. 
  

  

  " 
  I 
  also 
  detected 
  the 
  larvse 
  and 
  pupse 
  of 
  a 
  smaller 
  species 
  of 
  fly 
  called 
  

   Drosophila, 
  which 
  hatched 
  in 
  the 
  middle 
  of 
  August 
  with 
  the 
  foregoing 
  

   insects. 
  They 
  are 
  also 
  inhabitants 
  of 
  cellars, 
  as 
  their 
  specific 
  name 
  

   implies, 
  where 
  the 
  larvse 
  are 
  usually 
  very 
  abundant 
  all 
  the 
  year 
  round. 
  

   They 
  will 
  breed 
  in 
  stale 
  beer, 
  and 
  probably 
  are 
  generated 
  where 
  there 
  

   is 
  any 
  leakage 
  from 
  the 
  tap 
  and 
  oozing 
  about 
  the 
  bung, 
  as 
  well 
  as 
  from 
  

   the 
  fungi 
  which 
  spring 
  up 
  round 
  rotten 
  wood, 
  etc., 
  in 
  cellars. 
  I 
  have 
  

   also 
  known 
  them 
  to 
  be 
  bred 
  from 
  vinegar, 
  and 
  it 
  will 
  be 
  remembered 
  

   that 
  one 
  species, 
  D. 
  ilava, 
  lives 
  on 
  the 
  pulpy 
  substance 
  of 
  the 
  turnip- 
  

   leaves, 
  and 
  another, 
  D. 
  graminum, 
  I 
  have 
  bred 
  from 
  cabbage-leaves. 
  

   In 
  spring 
  and 
  autumn 
  the 
  flies 
  abound, 
  and 
  are 
  not 
  unfrequently 
  on 
  the 
  

   inside 
  of 
  our 
  windows. 
  They 
  belong 
  to 
  the 
  family 
  Muscidje 
  and 
  the 
  

   genus 
  DrosopUla. 
  That 
  bred 
  from 
  the 
  potatoes 
  appears 
  to 
  be 
  the 
  

   Linnean 
  species 
  named 
  

  

  ^^ 
  Drosophila 
  cellaris. 
  — 
  It 
  is 
  1^ 
  line 
  loug, 
  and 
  expands 
  4 
  lines 
  ; 
  the 
  general 
  color 
  is 
  ochre- 
  

   ous 
  ; 
  the 
  head 
  is 
  broad 
  as 
  well 
  as 
  the 
  face, 
  in 
  the 
  center 
  of 
  which 
  are 
  inserted 
  the 
  two 
  little 
  

   drooping 
  pubescent 
  horns, 
  the 
  third 
  joint 
  is 
  oval, 
  and 
  from 
  the 
  back 
  arises 
  a 
  feathery 
  

   bristlo 
  jointed 
  at 
  the 
  base 
  ; 
  the 
  orifice 
  forming 
  the 
  mouth 
  is 
  very 
  large 
  ; 
  eyes 
  large, 
  hemi- 
  

   spberical 
  ; 
  ocelli 
  three 
  on 
  the 
  crown 
  ; 
  thorax 
  globose-quadrate 
  ; 
  scutal 
  semi-ovate 
  ; 
  abdo- 
  

   men 
  small, 
  depressed, 
  oval, 
  blackish, 
  and 
  six-join 
  ted, 
  with 
  four 
  orfiveochreous 
  bauds; 
  the 
  

   apex 
  pointed 
  in 
  the 
  female; 
  wings 
  incumbent 
  in 
  repose, 
  very 
  long, 
  and 
  ample, 
  yel- 
  

   lowish 
  and 
  iridescent, 
  with 
  a 
  very 
  short 
  marginal 
  cell, 
  and 
  four 
  longitudinal 
  nervures, 
  

   the 
  second 
  and 
  third 
  united 
  toward 
  the 
  base, 
  the 
  third 
  and 
  fourth 
  toward 
  the 
  mar- 
  

   gin 
  ; 
  balancers 
  small, 
  clavate 
  ; 
  six 
  legs, 
  tapering 
  ; 
  feet 
  long, 
  slender, 
  and 
  five-joiuted, 
  

   terminated 
  by 
  minute 
  claws. 
  

  

  47 
  G 
  S 
  

  

  