﻿AQUATIC 
  INSECTS 
  IN 
  THE 
  ADIRONDACKS 
  

  

  469 
  

  

  Strikingly 
  large 
  size, 
  and 
  its 
  habit 
  of 
  flying 
  into 
  houses 
  not 
  unfrequently, 
  

   and 
  its 
  apparent 
  migrations 
  in 
  numbers, 
  have 
  made 
  it 
  a 
  rather 
  well 
  

   known 
  species. 
  

  

  Since 
  the 
  nymph 
  has 
  been 
  described 
  and 
  figured 
  by 
  Cabot, 
  it 
  will 
  suf- 
  

   fice 
  here 
  to 
  give 
  a 
  brief 
  statement 
  of 
  its 
  more 
  distinctive 
  characters. 
  

  

  Nymph. 
  Apparently 
  full 
  grown, 
  measures 
  in 
  total 
  length 
  46 
  mm; 
  

   abdomen 
  32 
  mm 
  ; 
  hind 
  femur 
  7.5 
  mm 
  ; 
  

   width 
  of 
  head 
  10 
  mm, 
  of 
  abdomen 
  

   10 
  mm. 
  

  

  Body 
  very 
  elongate, 
  widest 
  across 
  the 
  

   eyes 
  and 
  the 
  seventh 
  and 
  eighth 
  ab- 
  

   dominal 
  segments. 
  Head 
  flat, 
  much 
  

   narrowed 
  behind 
  the 
  eyes, 
  with 
  a 
  deep, 
  

   well 
  rounded 
  concavity 
  on 
  the 
  hind 
  mar- 
  

   gin, 
  and 
  obtuse 
  hind 
  angles 
  ; 
  labium 
  

   long 
  extending 
  posteriorly 
  between 
  the 
  

   bases 
  of 
  the 
  middle 
  legs; 
  mentum 
  

   (fig. 
  13) 
  with 
  sides 
  parallel 
  for 
  half 
  its 
  

   length, 
  then 
  suddenly 
  widened 
  in 
  a 
  regu- 
  

   lar 
  curve 
  to 
  the 
  bases 
  of 
  the 
  lateral 
  

   lobes; 
  median 
  lobe 
  with 
  convex 
  front 
  

   border 
  divided 
  by 
  a 
  shallow 
  open 
  cleft, 
  

   bearing 
  a 
  fringe 
  of 
  short 
  scales 
  on 
  either 
  

   side 
  of 
  the 
  cleft 
  ; 
  lateral 
  lobe 
  truncate 
  

   on 
  tip 
  with 
  a 
  short 
  hook 
  on 
  inner 
  angle 
  

   at 
  tip, 
  before 
  which 
  are 
  some 
  12 
  to 
  15 
  

   denticles. 
  

  

  Abdomen 
  with 
  an 
  obtuse 
  middorsal 
  

   ridge 
  ; 
  lateral 
  spines 
  on 
  segments 
  5-9, 
  

   mcreasmg 
  m 
  size 
  posteriorly, 
  on 
  9 
  hardly 
  Fabl, 
  from 
  within. 
  Photo 
  by 
  j. 
  g. 
  Needham 
  

   longer 
  than 
  half 
  of 
  the 
  length 
  of 
  the 
  

  

  loth 
  segment, 
  but 
  broadly 
  triangular; 
  superior 
  appendage 
  almost 
  as 
  long 
  

   as 
  the 
  inferiors, 
  not 
  cleft 
  at 
  apex; 
  laterals 
  half 
  as 
  long, 
  inferiors 
  not 
  quite 
  

   as 
  long 
  as 
  segments 
  9 
  and 
  10 
  together. 
  

  

  AESCHNA 
  

  

  Three 
  closely 
  related 
  species 
  of 
  this 
  genus 
  are 
  known 
  from 
  the 
  state. 
  

   Male 
  imagos 
  of 
  these 
  species 
  may 
  be 
  separated 
  by 
  the 
  following 
  key. 
  

  

  KEY 
  TO 
  SPECIES 
  OF 
  AESCHNA 
  

  

  a 
  Anal 
  triangle 
  of 
  hind 
  wing 
  of 
  male 
  consisting 
  usually 
  of 
  three 
  cells. 
  Superior 
  

   abdominal 
  appendages 
  of 
  male 
  with 
  a 
  promiuent 
  inferior 
  spine 
  at 
  the 
  distal 
  

   end 
  ; 
  genital 
  valve 
  of 
  female 
  strongly 
  elevated 
  at 
  the 
  apex 
  .. 
  const 
  r 
  iota 
  

   aa 
  Anal 
  triangle 
  of 
  the 
  hind 
  wing 
  of 
  the 
  male 
  consisting 
  generally 
  of 
  two 
  cells 
  ; 
  

   superior 
  appendage 
  of 
  the 
  male 
  without 
  j)rominent 
  inferior 
  spine 
  ; 
  genital 
  

   valve 
  of 
  female 
  not 
  strongly 
  elevated 
  at 
  its 
  apex 
  

   & 
  Superior 
  abdominal 
  appendages 
  of 
  the 
  male 
  with 
  a 
  superior 
  longitudinal 
  

  

  carina 
  denticulated 
  clepsyd 
  ra 
  

  

  Ih 
  Superior 
  appendages 
  of 
  the. 
  male 
  with 
  the 
  superior 
  longitudinal 
  carina 
  not 
  

   denticulated 
  verticalis 
  

  

  