﻿XIV 
  

  

  the 
  w'uKjed 
  (uhilt^ 
  appeared 
  on 
  the 
  satne 
  dale 
  in 
  eadi, 
  year. 
  At 
  Ur- 
  

   bana, 
  accordinu; 
  to 
  Professor 
  Johnson, 
  the 
  e^gs 
  had 
  not 
  yet 
  hatched 
  

   May 
  8, 
  1(S95. 
  Such 
  variations 
  as 
  these 
  suggest 
  quite 
  a 
  marked 
  sus- 
  

   ceptibility 
  to 
  meteorological 
  influences, 
  but 
  just 
  what 
  these 
  influ- 
  

   ences 
  are 
  the 
  notes 
  do 
  not 
  indicate. 
  One 
  might 
  conjecture, 
  however, 
  

   since 
  the 
  insects 
  pass 
  the 
  winter 
  in 
  almost 
  complete 
  exposure 
  to 
  the 
  

   weather 
  without 
  serious 
  injury, 
  that 
  the 
  efl^ect 
  of 
  the 
  climate 
  upon 
  

   them 
  is 
  possibly 
  quite 
  as 
  much 
  indirect 
  (through 
  the 
  deferred 
  elabo- 
  

   ration 
  of 
  the 
  sap 
  of 
  the 
  tree) 
  as 
  direct 
  — 
  through 
  the 
  cold. 
  

  

  DESCRIPTIVE. 
  

  

  In 
  preparing 
  the 
  following 
  descriptions 
  I 
  have 
  made 
  free 
  use 
  of 
  

   those 
  given 
  by 
  previous 
  students 
  of 
  this 
  insect, 
  adding 
  notes 
  and 
  

   comments 
  whenever 
  my 
  own 
  observations 
  are 
  divergent. 
  

  

  The 
  Eggs. 
  

  

  "The 
  eggs, 
  found 
  in 
  downy 
  balls, 
  vary 
  from 
  live 
  to 
  sixty 
  or 
  more 
  in 
  number; 
  

   usually, 
  however, 
  they 
  are 
  few. 
  They 
  are 
  yellowish, 
  slightly 
  ovate, 
  with 
  a 
  

   longitudinal 
  diameter 
  of 
  0.34 
  mm. 
  and 
  transverse 
  diameter 
  of 
  0.17 
  mm. 
  In 
  

   development 
  the 
  mouth 
  parts 
  are 
  first 
  apparent, 
  and 
  afterward 
  antenna^ 
  and 
  

   legs 
  appear, 
  these 
  being 
  fully 
  developed 
  by 
  the 
  time 
  the 
  larva 
  breaks 
  the 
  

   egg-erust." 
  — 
  Osborn. 
  

  

  Eggs 
  examined 
  by 
  Professor 
  Johnson 
  at 
  Urbana 
  April 
  IcS, 
  1895, 
  

   were 
  "0.38 
  mm.x0.19 
  mm.; 
  color 
  brownish 
  or 
  amber; 
  surface 
  rather 
  

   smooth, 
  but 
  covered 
  more 
  or 
  less 
  by 
  threads 
  of 
  the 
  woolly 
  excretion." 
  

   My 
  own 
  measurements 
  of 
  the 
  width 
  vary 
  from 
  0.156 
  mm. 
  to 
  0.173 
  mm. 
  

   and 
  of 
  the 
  length 
  0.312 
  mm. 
  to 
  0.346 
  mm., 
  an 
  average 
  of 
  all 
  measure- 
  

   ments 
  made 
  being 
  0.163 
  mm. 
  X 
  0.329 
  mm. 
  The 
  color 
  of 
  the 
  eggs 
  varies 
  

   slightly 
  from 
  yellowish 
  or 
  amber 
  to 
  brownish 
  amber, 
  sometimes 
  with 
  

   a 
  reddish 
  tint. 
  

  

  On 
  April 
  17 
  sixty-four 
  eggs 
  were 
  taken 
  from 
  the 
  trees 
  and 
  divided 
  

   into 
  three 
  groups, 
  consisting 
  of 
  twenty, 
  twenty, 
  and 
  seventeen 
  eggs 
  

   respectively. 
  Each 
  group 
  was 
  placed 
  on 
  one 
  of 
  the 
  ordinary 
  glass 
  

   slips 
  used 
  in 
  microscopic 
  work, 
  and 
  surrounded 
  by 
  a 
  ring 
  of 
  albumen 
  

   flxative. 
  which 
  interposed 
  an 
  efl:'ectual 
  barrier 
  to 
  the 
  escape 
  of 
  the 
  

   larv.v 
  when 
  they 
  should 
  be 
  hatched. 
  The 
  slides 
  were 
  examined 
  ev- 
  

   ery 
  morning 
  until 
  hatching 
  had 
  certainly 
  ceased. 
  From 
  the 
  first 
  

   were 
  taken 
  nineteen 
  larvte, 
  from 
  the 
  second 
  twenty, 
  from 
  the 
  third 
  

   thirteen, 
  giving 
  a 
  total 
  of 
  fifty-two 
  or 
  >^\\ 
  per 
  cent, 
  of 
  the 
  eggs 
  origi- 
  

   nally 
  placed 
  on 
  the 
  slides. 
  

  

  By 
  means 
  of 
  slides 
  prepared 
  in 
  the 
  same 
  way. 
  four 
  experiments 
  

   were 
  made 
  for 
  the 
  purpose 
  of 
  determining 
  the 
  period 
  of 
  incubation. 
  

   The 
  following 
  are 
  the 
  results 
  in 
  tabulated 
  form: 
  

  

  No. 
  

  

  of 
  

  

  Exp. 
  

  

  Date 
  of 
  Di'positidii. 
  Dateof 
  Hatching'. 
  

  

  j 
  Period 
  

   !of 
  Incubation. 
  

  

  f 
  Between 
  April 
  17, 
  10 
  ji. 
  ni.,andlS. 
  I 
  Between 
  April 
  23,10 
  a. 
  m.. 
  and 
  24, 
  ( 
  

   1 
  It 
  a. 
  m 
  J 
  ! 
  8 
  a. 
  m 
  I 
  

  

  jBetwe..nApriI18. 
  12 
  m.. 
  and20. 
  JUp^j,25j,efore8a.m 
  { 
  

  

  l^s^m"^'!"*'^^:^"'''"':*"!'^^^^ 
  { 
  

  

  April 
  29, 
  10 
  a. 
  Ill 
  !May 
  5, 
  between 
  10 
  a. 
  in. 
  and 
  5 
  p. 
  m. 
  | 
  

  

  