﻿LOEW 
  ON 
  THE 
  EYE 
  GALL-GNAT. 
  [7] 
  

  

  malformations 
  arising 
  therefrom, 
  can 
  be 
  mucli 
  easier 
  recognized 
  than 
  

   those 
  irrelevant 
  characters. 
  Without 
  a 
  very 
  close 
  comparison 
  of 
  the 
  

   natural 
  specimens 
  of 
  the 
  perfect 
  insect, 
  the 
  identity 
  or 
  the 
  difference 
  of 
  

   species 
  is 
  often 
  very 
  difficult 
  to 
  prove. 
  And 
  yet 
  this 
  must 
  be 
  accurately 
  

   shown 
  before 
  it 
  is 
  allowed 
  to 
  declare 
  two 
  species 
  as 
  one 
  and 
  the 
  same. 
  

   As 
  long 
  as 
  there 
  are 
  only 
  presumptions 
  as 
  to 
  their 
  identity, 
  the 
  throw- 
  

   ing 
  together 
  and 
  uniting 
  of 
  them 
  leads 
  to 
  new, 
  increased 
  confusion, 
  

   while 
  the 
  most 
  accurate 
  distinguishing 
  and 
  the 
  most 
  scrupulous 
  care 
  in 
  

   separating 
  allied 
  species, 
  and 
  not 
  confusing 
  them 
  as 
  one 
  species, 
  war- 
  

   rants 
  and 
  secures 
  our 
  knowledge. 
  

  

  That 
  the 
  whole 
  life-history 
  of 
  the 
  Hessian 
  fly 
  closely 
  agrees 
  with 
  that 
  

   of 
  our 
  rye 
  gall-gnat 
  cannot 
  be 
  denied; 
  yet 
  it 
  would 
  be 
  hasty 
  to 
  take 
  this 
  

   congruity, 
  which 
  in 
  closely 
  allied 
  species 
  cannot 
  at 
  all 
  be 
  expected 
  less, 
  

   for 
  a 
  proof 
  of 
  the 
  identity 
  of 
  the 
  two 
  species. 
  Moreover 
  we 
  find 
  also 
  

   some 
  small 
  differences. 
  The 
  Ceeidomyia 
  destructor 
  almost 
  exclusively 
  at- 
  

   tacks 
  wheat 
  only, 
  while 
  our 
  rye 
  gall-gnat 
  has 
  hitherto 
  been 
  found 
  on 
  rye 
  

   only. 
  The 
  maggots 
  and 
  pupse 
  of 
  the 
  winter 
  generation 
  of 
  Ceeidomyia 
  

   destructor 
  are 
  said 
  to 
  occur 
  always 
  only 
  just 
  above 
  the 
  upper 
  end 
  of 
  the 
  

   root- 
  stock, 
  and 
  those 
  of 
  the 
  rye 
  gall-gnat 
  are 
  usually 
  found 
  a 
  little 
  

   higher. 
  These 
  differences 
  are 
  too 
  trifling 
  to 
  disprove 
  the 
  identity 
  of 
  the 
  

   two 
  species. 
  Rye 
  and 
  wheat 
  are 
  such 
  closely 
  allied 
  plants 
  that 
  a 
  gall- 
  

   gnat, 
  otherwise 
  a 
  very 
  stubborn 
  animal 
  as 
  regards 
  the 
  selection 
  of 
  a 
  

   certain 
  plant, 
  would 
  very 
  likely 
  choose, 
  according 
  to 
  the 
  inclination 
  of 
  

   the 
  circumstances, 
  one 
  or 
  the 
  other 
  of 
  the 
  two 
  kinds 
  of 
  plants. 
  Moreover 
  

   it 
  is 
  not 
  yet 
  proved 
  whether 
  our 
  rye 
  gall-gnat 
  does 
  not 
  infest 
  wheat 
  also. 
  

  

  I 
  shall 
  now 
  compare 
  the 
  insect 
  in 
  its 
  different 
  stages 
  of 
  development, 
  

   I 
  could 
  not 
  procure 
  any 
  specimens 
  of 
  the 
  American 
  (Hessian) 
  fly, 
  nor 
  

   was 
  I 
  able 
  to 
  find 
  any 
  in 
  a 
  zoological 
  or 
  private 
  museum. 
  Therefore 
  I 
  

   must 
  depend 
  upon 
  Asa 
  Fitch's 
  descriptions 
  and 
  illustrations. 
  I 
  notice 
  

   a 
  conspicuous 
  difference 
  already 
  in 
  the 
  shape 
  of 
  the 
  brown 
  shell 
  sur- 
  

   rounding 
  the 
  pupa 
  proper. 
  This 
  shell 
  is 
  less 
  cylindrical 
  and 
  comparatively 
  

   broader 
  than 
  in 
  our 
  rye 
  gall-gnat, 
  yet 
  much 
  more 
  pointed 
  at 
  its 
  tapering 
  

   end, 
  while 
  in 
  our 
  species 
  it 
  is 
  blunt, 
  conical. 
  Fitch 
  counts 
  in 
  the 
  an- 
  

   tennse 
  of 
  the 
  perfect 
  insect 
  16 
  joints, 
  while 
  they 
  are 
  18-jointed 
  in 
  all 
  

   my 
  specimens. 
  Moreover, 
  according 
  to 
  his 
  description, 
  the 
  different 
  an- 
  

   tennal 
  joints 
  are 
  in 
  the 
  female 
  connected 
  by 
  thin 
  pedicels 
  that 
  are 
  one- 
  

   third 
  of 
  the 
  length 
  of 
  the 
  joints, 
  the 
  last 
  joint 
  being 
  at 
  least 
  one-third 
  

   longer 
  than 
  the 
  penultimate 
  joint 
  ; 
  the 
  intervening 
  pedicels 
  between 
  

   the 
  joints 
  of 
  the 
  female 
  rye 
  gall-gnat 
  are 
  so 
  short 
  that 
  the 
  joints 
  appear 
  

   to 
  sit 
  one 
  'on 
  top 
  of 
  the 
  other 
  and 
  the 
  last 
  joint 
  is 
  scarcely 
  longer 
  than 
  

   the 
  preceding. 
  I 
  therefore 
  infer 
  that 
  if 
  our 
  species 
  is 
  the 
  real 
  Ceeido- 
  

   myia 
  destructor 
  J 
  the 
  demonstration 
  of 
  the 
  pui)a 
  and 
  the 
  female 
  antennae 
  

   given 
  by 
  Mr. 
  A. 
  Fitch 
  must 
  be 
  wrong, 
  and 
  that,' 
  if 
  he 
  correctly 
  de- 
  

   scribes 
  it, 
  our 
  rye 
  gall-gnat 
  must 
  be 
  regarded 
  as 
  different 
  from 
  Ceeidomyia 
  

   destructor. 
  The 
  question 
  can 
  only 
  i)roperly 
  be 
  answered 
  by 
  a 
  compari- 
  

   son 
  with 
  original 
  American 
  specimens, 
  which 
  I 
  soon 
  expect 
  to 
  receive. 
  

   Without 
  a 
  verification 
  we 
  cannot 
  suppose 
  any 
  inaccuracy 
  in 
  such 
  a 
  

   thorough 
  entomologist 
  as 
  A. 
  Fitch. 
  We 
  now 
  have, 
  therefore, 
  to 
  regard 
  

   our 
  rye 
  fly 
  as 
  different 
  from 
  Ceeidomyia 
  destructor 
  and 
  to 
  call 
  it 
  Ceeid- 
  

   omyia 
  secalina. 
  

  

  DESCRIPTION 
  OF 
  THE 
  RYE 
  GALL- 
  GNAT. 
  

  

  Female 
  rye 
  gall-gnat 
  {Ceeidomyia 
  secalina). 
  — 
  The 
  length 
  from 
  the 
  front 
  

   to 
  the 
  extensile 
  ovipositor 
  is 
  about 
  IJ 
  lines. 
  Body- 
  color 
  black 
  ; 
  humerus, 
  

   region 
  under 
  the 
  alar 
  radicle, 
  nearly 
  the 
  whole 
  abdomen 
  and 
  the 
  con- 
  

   necting 
  membranes 
  of 
  the 
  abdominal 
  segments 
  blood-red 
  ; 
  the 
  ovi- 
  

   positor, 
  consisting 
  of 
  two 
  parts, 
  is 
  more 
  of 
  the 
  color 
  of 
  vermilion, 
  fur- 
  

   nished 
  at 
  its 
  end 
  with 
  two 
  very 
  minute, 
  almost 
  round, 
  lamellulse. 
  The 
  

  

  