﻿PACKARD] 
  THE 
  EMBRYO 
  LOCUST. 
  633 
  

  

  amnion, 
  I 
  was 
  able 
  to 
  plainly 
  see 
  in 
  a 
  specimen, 
  which 
  the 
  moment 
  after 
  

   the 
  amnion 
  was 
  forced 
  back 
  from 
  the 
  head 
  opened 
  the 
  jaws 
  and 
  thrust 
  

   out 
  the 
  palpi 
  and 
  antennoe. 
  The 
  amnion 
  is 
  sometimes 
  nearly 
  shed 
  be- 
  

   fore 
  the 
  embryo 
  has 
  entirely 
  extricated 
  itself 
  from 
  the 
  egg-siiell. 
  The 
  

   outer 
  embryonal 
  layer, 
  or 
  " 
  serous 
  membrane" 
  of 
  Kowalevsky,may 
  be 
  de- 
  

   tected 
  by 
  rubbing 
  off 
  the 
  chorion. 
  

  

  I 
  have 
  found 
  six 
  stages 
  in 
  the 
  life-history 
  of 
  the 
  Eocky 
  Mountain 
  

   locust, 
  with 
  consequently 
  five 
  molts, 
  with 
  the 
  following 
  characters 
  as 
  

   seen 
  in 
  the 
  female 
  sex 
  of 
  each 
  stage 
  : 
  

  

  1. 
  First 
  larval. 
  Head 
  very 
  large, 
  and 
  abdomen 
  short' 
  and 
  small 
  5 
  

   antenufle 
  12-joiuted. 
  Length, 
  14-15"^™. 
  

  

  2. 
  Second 
  larval. 
  Head 
  smaller; 
  antennae 
  16 
  jointed; 
  lower 
  edges 
  

   of 
  tergum 
  of 
  meso-thoracic 
  ring 
  and 
  especially 
  meta-thoracic 
  full 
  and 
  

   rounded. 
  No 
  difference 
  from 
  the 
  first 
  stage 
  seen 
  in 
  a 
  dorsal 
  view 
  ; 
  colors 
  

   deeper, 
  markings 
  more 
  distinct. 
  Length, 
  T-S^"""^. 
  

  

  3. 
  Third 
  larval. 
  Head 
  about 
  the 
  same 
  size 
  proportionally 
  as 
  in 
  the 
  

   second 
  stage 
  ; 
  lower 
  sides 
  of 
  meso- 
  and 
  meta-thoracic 
  rings 
  subacutely 
  

   produced, 
  evidently 
  the 
  rudiments 
  of 
  the 
  wing-pods 
  of 
  the 
  pupa. 
  The 
  

   proportion 
  of 
  the 
  prothorax 
  to 
  the 
  two 
  posterior 
  segments 
  is 
  the 
  same 
  

   as 
  before. 
  Length, 
  9-11"''". 
  

  

  4. 
  First 
  pupal. 
  Antennte 
  20-jointed; 
  prothorax 
  much 
  produced 
  back- 
  

   ward, 
  wing-pods 
  well 
  developed, 
  covering 
  the 
  tergum 
  of 
  the 
  meso- 
  and 
  

   meta-thoracic 
  segments, 
  so 
  far 
  as 
  they 
  are 
  not 
  concealed 
  by 
  the 
  over- 
  

   lapping 
  of 
  the 
  prothorax 
  ; 
  outer 
  pair 
  twice 
  as 
  large 
  as 
  the 
  inner 
  pair; 
  

   the 
  hinder 
  pair 
  2|™™ 
  in 
  length, 
  or 
  two-thirds 
  as 
  long 
  as 
  the 
  prothorax. 
  

   Length, 
  15"'™. 
  

  

  5. 
  Second 
  pupal. 
  Antennoe 
  22jointed; 
  prothorax 
  still 
  larger; 
  hind 
  

   wing-pods 
  as 
  long 
  as 
  the 
  prothorax. 
  Length 
  20™"^ 
  (1 
  inch). 
  

  

  6. 
  Imago, 
  or 
  adult, 
  with 
  wings 
  fully 
  developed. 
  Antennte 
  23-24- 
  

   jointed 
  ; 
  eyes 
  more 
  rounded 
  than 
  in 
  the 
  pupa 
  ; 
  hind 
  femora 
  slenderer. 
  

   Length 
  of 
  body, 
  25"°^. 
  

  

  It 
  will 
  thus 
  be 
  seen 
  that 
  there 
  are 
  three 
  larval 
  and 
  two 
  pupal 
  stages 
  

   besides 
  the 
  adult 
  stage. 
  

  

  The 
  embryo 
  locust 
  — 
  On 
  removing 
  the 
  living 
  embryo 
  from 
  the 
  egg-shell 
  

   under 
  (Plate 
  LXII, 
  Fig. 
  2), 
  it 
  is 
  found 
  that 
  it 
  lies 
  with 
  the 
  legs 
  folded 
  on 
  

   the 
  side 
  of 
  the 
  body, 
  the 
  fore 
  and 
  middle 
  pair 
  folded 
  directly 
  across 
  the 
  

   thorax, 
  while 
  the 
  hind 
  pair 
  are 
  laid 
  along 
  each 
  side 
  of 
  the 
  abdomen. 
  

   The 
  antennie 
  lie 
  on 
  the 
  face 
  each 
  side 
  of 
  the 
  clypeus 
  and 
  labrum, 
  or 
  

   upper 
  lip. 
  The 
  eyes 
  are 
  dark 
  reddish, 
  and 
  the 
  head, 
  limbs, 
  and 
  cross- 
  

   lines 
  on 
  the 
  back 
  of 
  the 
  body 
  are 
  reddish 
  mixed 
  with 
  yellow. 
  Beneath, 
  

   the 
  body 
  and 
  legs 
  are 
  white. 
  By 
  putting 
  the 
  eggs 
  in 
  alcohol 
  the 
  shell 
  

   becomes 
  more 
  transparent, 
  so 
  that 
  the 
  head, 
  eyes, 
  limbs, 
  and 
  reddish 
  

   portions 
  of 
  the 
  body 
  become 
  visible. 
  Length 
  of 
  embryo 
  at 
  time 
  of 
  

   hatching 
  0.21 
  inch. 
  Described 
  from 
  living 
  specimens 
  received 
  from 
  Mr 
  

   S. 
  D. 
  Payne, 
  Kasota, 
  Lesueur 
  County, 
  Minnesota, 
  March 
  1, 
  1877.* 
  

   Either 
  during 
  the 
  night 
  of 
  the 
  13th 
  or 
  early 
  in 
  the 
  morning 
  of 
  the 
  14th 
  

   of 
  March 
  nearly 
  all 
  the 
  larvse 
  (the 
  eggs 
  having 
  been 
  kept 
  in 
  a 
  warm 
  

   room) 
  hatched 
  at 
  the 
  same 
  time. 
  The 
  egg-shell 
  bursts 
  open 
  at 
  the 
  head- 
  

   end, 
  when 
  the 
  larva 
  immediately 
  after 
  extricating 
  itself 
  from 
  the 
  egg 
  

   casts 
  off 
  a 
  thin 
  pellicle 
  (the 
  amnion 
  or 
  faUe7ihlatt), 
  as 
  I 
  have 
  seen 
  in 
  

   the 
  larv?B 
  of 
  the 
  ilea, 
  currant 
  saw-fly, 
  and 
  other 
  insects. 
  Before 
  the 
  

   skin 
  is 
  cast 
  it 
  is 
  almost 
  motionless, 
  and 
  by 
  slight 
  movements 
  of 
  the 
  

   body 
  in 
  about 
  five 
  minutes 
  draws 
  itself 
  out 
  of 
  the 
  amnion. 
  The 
  pro- 
  

  

  * 
  This 
  shows 
  that 
  the 
  embryo 
  locust 
  develops 
  iu 
  the 
  autumn 
  immediately 
  after 
  the 
  

   eggs 
  are 
  laid, 
  and 
  that 
  it 
  lies 
  dormant 
  (a 
  few 
  occasionally 
  hatching 
  in 
  the 
  autumn) 
  

   during 
  the 
  winter, 
  ready 
  to 
  hurst 
  its 
  egg-shell 
  in 
  the 
  spring. 
  

  

  