﻿xn 
  

  

  tion 
  of 
  the 
  dates 
  of 
  the 
  life 
  history 
  of 
  HeiiiGrobius, 
  as 
  shown 
  in 
  the 
  cal- 
  

   endar, 
  indicates 
  that 
  the 
  larva 
  of 
  this 
  insect 
  may 
  have 
  been 
  at 
  work 
  

   at 
  about 
  the 
  same 
  time. 
  

  

  3. 
  A 
  little 
  later 
  (middle 
  to 
  the 
  last 
  of 
  May) 
  the 
  attack 
  is 
  taken 
  up 
  

   by 
  LcHCopis 
  simplex 
  and 
  Henierobius 
  altermms, 
  reaching 
  in 
  its 
  turn 
  

   a 
  climax 
  of 
  severity, 
  about 
  May 
  211, 
  scarcely 
  less 
  acute 
  than 
  that 
  of 
  

   the 
  preceding 
  onslaught. 
  This 
  period 
  covers 
  that 
  during 
  which 
  the 
  

   young 
  of 
  CAe?*7Hr'.s' 
  progress 
  to 
  -the 
  winged 
  form 
  and 
  lasts 
  until 
  the 
  

  

  latter 
  disappears. 
  i. 
  1 
  ^ 
  jlZj^Za 
  „ 
  _JL_j 
  \^' 
  22 
  .^ 
  ^^CZ3 
  

  

  ni4. 
  The 
  complete 
  series 
  of 
  transformations 
  in 
  the 
  Chermea 
  extended 
  

   from 
  April 
  S, 
  when 
  egg-laying 
  began, 
  to 
  May 
  9, 
  when 
  winged 
  adults 
  

   began 
  to 
  appear 
  — 
  a 
  period 
  of 
  one 
  month. 
  This 
  history 
  seems 
  to 
  be 
  

   reflected 
  to 
  a 
  certain 
  extent 
  in 
  the 
  lives 
  of 
  its 
  destroyers. 
  Thus, 
  the 
  

   ChrysojXi 
  attack 
  lasts 
  from 
  Apr. 
  15 
  to 
  May 
  \.'6\8yrpluis,hom. 
  Apr. 
  

   18 
  to 
  May 
  12; 
  Leticopis, 
  adult 
  to 
  adult, 
  Apr. 
  22 
  to 
  May 
  22; 
  Hcmero- 
  

   J)ius 
  adults 
  observed 
  May 
  8, 
  pupation 
  May 
  29. 
  In 
  the 
  last 
  two 
  the 
  

   period 
  of 
  feeding 
  is 
  somewhat 
  shorter 
  than 
  one 
  month, 
  but 
  will 
  not 
  

   fall 
  below 
  three 
  weeks 
  if 
  we 
  consider 
  the 
  history 
  of 
  the 
  species 
  as 
  a 
  

   whole 
  and 
  not 
  the 
  life 
  of 
  an 
  individual 
  merelj'. 
  

  

  5. 
  It 
  will 
  be 
  further 
  noted 
  tliat 
  this 
  difference 
  of 
  about 
  one 
  week 
  

   in 
  the 
  length 
  of 
  the 
  attacks 
  made 
  by 
  Leucopis 
  and 
  Hemerohins, 
  con- 
  

   sequent 
  upon 
  their 
  shorter 
  periods 
  of 
  transformation, 
  results 
  in 
  dis- 
  

   tributing 
  the 
  total 
  attack 
  of 
  the 
  combined 
  enemies 
  of 
  Chermes 
  through 
  

   the 
  entire 
  time 
  from 
  the 
  opening 
  of 
  spring 
  to 
  the 
  disappearance 
  of 
  

   the 
  winged 
  form. 
  May 
  23. 
  

  

  Of 
  the 
  relations 
  existing 
  among 
  the 
  enemies 
  of 
  Clwi'nies 
  themselves, 
  

   it 
  may 
  be 
  said 
  that 
  the 
  Chrysopa, 
  Sjjrplin.<t, 
  and 
  Hemcrobms 
  prob- 
  

   ably 
  prey 
  upon 
  the 
  Leucopis, 
  as 
  the 
  first 
  two 
  certainly 
  do 
  upon 
  each 
  

   other 
  and 
  the 
  Si/rphii>^ 
  upon 
  its 
  own 
  kind. 
  

  

  USE 
  OF 
  INSECTICIDES. 
  

  

  An 
  examination 
  of 
  the 
  calendar 
  indicates 
  that 
  the 
  best 
  time 
  to 
  de- 
  

   stroy 
  the 
  Chermes 
  with 
  insecticides 
  is 
  probably 
  in 
  the 
  winter 
  or 
  early 
  

   spring. 
  If 
  force 
  enough 
  be 
  applied 
  to 
  the 
  spray 
  the 
  presence 
  of 
  the 
  

   ■'wool" 
  need 
  not 
  be 
  disadvantageous, 
  and 
  if 
  the 
  spraying 
  be 
  done 
  in 
  

   the 
  winter 
  the 
  natural 
  enemies 
  of 
  the 
  Chermes 
  will 
  escape 
  the 
  appli- 
  

   cation. 
  But 
  one 
  experiment 
  has 
  been 
  made 
  at 
  Urbana 
  in 
  this 
  line. 
  

   The 
  kerosene 
  emulsion 
  was 
  used, 
  the 
  sj^ray 
  l)cing 
  applied 
  May 
  8, 
  1895. 
  

   At 
  this 
  time 
  the" 
  eggs 
  had 
  not 
  hatched. 
  Professor 
  Johnson, 
  who 
  made 
  

   the 
  experiment, 
  records 
  that 
  no 
  lice 
  had 
  made 
  their 
  appearance, 
  up 
  

   to 
  Aug. 
  7, 
  on 
  the 
  tree 
  treated, 
  while 
  all 
  other 
  trees 
  that 
  had 
  been 
  in- 
  

   fested 
  were 
  covered 
  by 
  them. 
  This 
  experiment 
  seems 
  to 
  be 
  conclu- 
  

   sive 
  not 
  onlv 
  fis^ 
  to 
  the 
  lice 
  but 
  as 
  regards 
  tlie 
  eggs 
  also. 
  

  

  