﻿AQUATIC 
  INSECTS 
  IN 
  THE 
  ADIRONDACKS 
  579 
  

  

  thoracic 
  three 
  times 
  as 
  long 
  as 
  the 
  prothoracic 
  segment, 
  smooth 
  except 
  

   for 
  a 
  single 
  piliferous 
  tubercle 
  each 
  side. 
  

  

  Abdominal 
  segments 
  1-7 
  similar, 
  and 
  of 
  nearly 
  equal 
  length, 
  each 
  

   bearing 
  three 
  rings 
  of 
  tubercles, 
  a 
  median 
  ring 
  of 
  tubercles 
  of 
  moderate 
  

   size, 
  and 
  at 
  each 
  end 
  close 
  beside 
  the 
  suture 
  separating 
  the 
  segments 
  a 
  

   ring 
  of 
  minute 
  tubercles; 
  median 
  ring, 
  with 
  the 
  pair 
  of 
  tubercles 
  beside 
  

   the 
  middorsal 
  line 
  (pi. 
  ^6, 
  fig. 
  3^) 
  very 
  mobile, 
  transversely 
  elongated, 
  

   bearing 
  a 
  stiff 
  brush 
  of 
  recurved 
  or 
  hooked 
  bristles, 
  well 
  adapted 
  for 
  crawl- 
  

   ing 
  beneath 
  the 
  surface 
  film 
  ; 
  on 
  the 
  ventral 
  side, 
  two 
  pairs 
  of 
  prominent 
  

   rounded 
  tubercles 
  ; 
  between 
  the 
  dorsal 
  and 
  the 
  ventral 
  there 
  are 
  on 
  either 
  

   side 
  four 
  or 
  five 
  lesser 
  tubercles, 
  mostly 
  unisetigerous, 
  sometimes 
  not 
  very 
  

   distinct, 
  the 
  third 
  of 
  them, 
  counting 
  from 
  above, 
  a 
  little 
  out 
  of 
  line, 
  in 
  

   advance 
  of 
  the 
  others. 
  There 
  is 
  a 
  broad 
  median 
  ventral 
  lobe 
  on 
  the 
  eighth 
  

   abdominal 
  segment, 
  liplike 
  rounded, 
  covered 
  with 
  very 
  minute 
  re- 
  

   curved 
  prickles. 
  

  

  Apex 
  of 
  the 
  abdomen 
  (pi. 
  7,6, 
  fig. 
  3^) 
  upturned, 
  flattened, 
  tipuloid, 
  

   fashioned 
  into 
  a 
  disk 
  which 
  surrounds 
  the 
  frmged 
  respiratory 
  apertures. 
  

   There 
  are 
  two 
  pairs 
  of 
  long 
  processes 
  on 
  the 
  ventral 
  half 
  of 
  the 
  margin 
  of 
  the 
  

   disk 
  and 
  three 
  pairs 
  of 
  lovr 
  tubercles 
  on 
  the 
  dorsal 
  half 
  of 
  it. 
  The 
  two 
  

   submedian 
  ventral 
  processes 
  are 
  long, 
  triangular, 
  almost 
  lanceolate, 
  simple; 
  

   those 
  of 
  the 
  pair 
  external 
  to 
  these 
  are 
  two-jointed, 
  the 
  joint 
  midway 
  

   their 
  length 
  ; 
  both 
  pairs 
  are 
  pilose, 
  and 
  about 
  equal 
  in 
  length 
  to 
  the 
  

   diameter 
  of 
  the 
  disk. 
  Respiratory 
  apertures 
  in 
  two 
  groups 
  of 
  three 
  

   each, 
  slitlike, 
  radiating 
  in 
  arrangement. 
  From 
  the 
  notches 
  between 
  the 
  

   apertures 
  and 
  at 
  their 
  sides 
  arise 
  tufts 
  of 
  black, 
  floating 
  filaments 
  

   arranged 
  in 
  a 
  flat 
  whorl, 
  well 
  adapted 
  to 
  holding 
  the 
  breathing 
  apertures 
  

   up 
  to 
  the 
  surface 
  of 
  the 
  water; 
  these 
  filaments 
  are 
  black, 
  dichotomously 
  

   (often 
  irregularly) 
  four 
  or 
  five 
  times 
  branched, 
  about 
  10 
  or 
  12 
  in 
  number, 
  

   and 
  extending 
  almost 
  to 
  the 
  margin 
  of 
  the 
  disk. 
  

  

  The 
  larva 
  when 
  undisturbed 
  lies 
  quietly 
  at 
  the 
  surface 
  of 
  the 
  water 
  

  

  amid 
  a 
  tangle 
  of 
  vegetation. 
  It 
  can 
  swim 
  when 
  disturbed, 
  and 
  its 
  

  

  swimming 
  is 
  most 
  curious. 
  It 
  pulls 
  itself 
  below 
  the 
  surface, 
  turns 
  over 
  on 
  

  

  its 
  back, 
  and 
  then 
  progresses 
  by 
  bending 
  and 
  straightening 
  its 
  body, 
  

  

  striking 
  the 
  water 
  sharply 
  with 
  the 
  flat 
  face 
  of 
  its 
  caudal 
  disk. 
  

  

  Puparium. 
  (PI. 
  14, 
  fig. 
  3-5). 
  Length 
  6 
  mm; 
  greatest 
  horizontal 
  

   diameter 
  3 
  mm; 
  vertical 
  diameter 
  2.5 
  mm. 
  

  

  Color 
  reddish 
  brown, 
  closely 
  marked 
  with 
  yellowish 
  on 
  the 
  ventral 
  side. 
  

   Body 
  shaped 
  like 
  an 
  undetermined 
  seed, 
  which 
  was 
  not 
  uncommon, 
  float- 
  

   ing 
  on 
  the 
  surface 
  of 
  the 
  creek. 
  I 
  first 
  mistook 
  the 
  pupae 
  for 
  seeds, 
  and 
  

   afterward 
  occasionally 
  mistook 
  seeds 
  for 
  pupae, 
  so 
  good 
  was 
  the 
  

   resemblance. 
  

  

  Body 
  ovate, 
  dorsally 
  flattened 
  and 
  ventrally 
  rounded, 
  broadly 
  canoe- 
  

   shaped, 
  but 
  suddenly 
  contracted 
  anteriorly 
  into 
  a 
  flat, 
  truncate, 
  rostral 
  

   prominence 
  .5 
  mm 
  wide 
  and 
  .9 
  mm 
  long. 
  There 
  is 
  a 
  black, 
  middorsal 
  

   curved 
  mark 
  (concave 
  anteriorly) 
  just 
  behind 
  the 
  base 
  of 
  this 
  beak. 
  

   (When 
  the 
  imago 
  emerges, 
  this 
  beak 
  splits 
  down 
  its 
  sharp 
  lateral 
  margins, 
  

   and 
  across 
  the 
  dorsum 
  of 
  the 
  body 
  near 
  to 
  the 
  aboved 
  mentioned 
  black 
  

   mark, 
  and 
  comes 
  off 
  as 
  one 
  half 
  of 
  the 
  cap.) 
  

  

  The 
  posterior 
  end 
  is 
  suddenly, 
  and 
  strongly 
  contracted 
  into 
  a 
  cylindric 
  

   tail, 
  which 
  is 
  directed 
  upward 
  at 
  an 
  angle 
  of 
  75° 
  with 
  the 
  axis 
  of 
  the 
  

   body. 
  The 
  float 
  of 
  the 
  larva 
  persists 
  on 
  the 
  summit 
  of 
  this 
  tail, 
  and 
  

  

  