﻿174 
  REPORT 
  UNITED 
  STATES 
  ENTOMOLOGICAL 
  COMMISSION. 
  

  

  which 
  is 
  about 
  the 
  time 
  the 
  red 
  currant 
  is 
  in 
  blossom, 
  and 
  the 
  larvae 
  

   acquire 
  their 
  full 
  size 
  in 
  from 
  three 
  to 
  four 
  weeks 
  thereafter. 
  

  

  Dr. 
  LeBaron 
  found 
  a 
  few 
  young 
  larvae 
  on 
  the 
  trees 
  in 
  Kane 
  County, 
  

   Illinois, 
  about 
  April 
  20, 
  1871, 
  but 
  he 
  says 
  they 
  were 
  evidently 
  prema- 
  

   ture 
  stragglers, 
  as 
  the 
  foliage 
  had 
  then 
  scarcely 
  begun 
  to 
  open. 
  . 
  But 
  

   on 
  April 
  27, 
  the 
  red 
  currant 
  being 
  in 
  pretty 
  full 
  bloom, 
  and 
  the 
  leaves 
  

   on 
  some 
  of 
  the 
  apple 
  trees 
  being 
  half 
  expanded, 
  he 
  found 
  almost 
  every 
  

   tuft 
  of 
  leaves 
  which 
  he 
  examined 
  occupied 
  by 
  two 
  or 
  three 
  minute 
  Can- 
  

   ker 
  Worms. 
  In 
  the 
  latitude 
  of 
  Saint 
  Louis 
  the 
  worms 
  have 
  generally 
  

   descended 
  the 
  trees 
  and 
  entered 
  the 
  ground 
  by 
  the 
  middle 
  of 
  May, 
  

   though 
  some 
  remain 
  till 
  about 
  the 
  first 
  of 
  June. 
  About 
  Lancaster, 
  

   Lancaster 
  County, 
  Pennsylvania, 
  they 
  attain 
  their 
  full 
  size 
  in 
  May, 
  and 
  

   go 
  into 
  the 
  ground 
  hj 
  the 
  first 
  of 
  June. 
  In 
  New 
  York 
  they 
  are 
  said 
  

   (if 
  the 
  species 
  which 
  occurs 
  there 
  is 
  vernata) 
  to 
  commit 
  their 
  ravages 
  

   during 
  the 
  last 
  of 
  May 
  and 
  first 
  of 
  June, 
  so 
  that 
  they 
  probably 
  complete 
  

   their 
  growth 
  toward 
  tlie 
  middle 
  of 
  June. 
  

  

  We 
  amply 
  prov^ed 
  during 
  the 
  summers 
  of 
  1868 
  and 
  1869 
  that 
  there 
  

   is 
  but 
  one 
  brood 
  each 
  year 
  in 
  Missouri, 
  just 
  as 
  there 
  is 
  but 
  one 
  brood 
  

   in 
  Maine, 
  and 
  at 
  whatever 
  time 
  the 
  worms 
  enter 
  the 
  ground 
  they 
  re- 
  

   main 
  there 
  as 
  chrysalids 
  all 
  through 
  the 
  summer 
  and 
  fall 
  months, 
  and 
  

   the 
  great 
  majority 
  of 
  them 
  till 
  the 
  following 
  spring. 
  Some, 
  indeed, 
  

   Dr. 
  Harris 
  says, 
  remain 
  in 
  the 
  ground 
  for 
  a 
  year 
  longer 
  than 
  the 
  bulk 
  

   of 
  the 
  brood. 
  A 
  frost 
  seems 
  to 
  be 
  necessary 
  to 
  their 
  proper 
  develop- 
  

   ment. 
  

  

  HABITS 
  OF 
  THE 
  WORMS. 
  — 
  The 
  little 
  Canker 
  Worms, 
  on 
  making 
  

   their 
  escape 
  from 
  the 
  egg, 
  cluster 
  upon 
  and 
  consume 
  the 
  tender 
  leaves, 
  

   and 
  on 
  the 
  approach 
  of 
  cold 
  or 
  wet 
  weather 
  creep 
  for 
  shelter 
  into 
  the 
  

   bosom 
  of 
  the 
  expanding 
  bud 
  or 
  into 
  the 
  opening 
  flowers. 
  

  

  They 
  feed 
  and 
  migrate 
  by 
  day, 
  remaining 
  stationary 
  during 
  the 
  night. 
  

   Like 
  most 
  other 
  span-worms 
  they 
  have 
  the 
  habit 
  of 
  resting 
  in 
  a 
  stiff, 
  

   straight 
  posture, 
  either 
  at 
  an 
  angle 
  of 
  about 
  45° 
  from 
  or 
  flat 
  and 
  par- 
  

   allel 
  with 
  the 
  twig 
  which 
  they 
  occupy, 
  and 
  in 
  these 
  positions 
  easily 
  

   elude 
  detection. 
  They 
  are 
  seldom 
  ever 
  noticed 
  upon 
  our 
  trees 
  till 
  the 
  

   riddled 
  and 
  seared 
  appearance 
  of 
  the 
  foliage 
  tells 
  of 
  their 
  presence. 
  

   The 
  leaves 
  first 
  attacked 
  will 
  be 
  found 
  pierced 
  with 
  small 
  holes, 
  which 
  

   become 
  larger 
  and 
  more 
  irregular 
  when 
  the 
  Canker 
  Worms 
  increase 
  in 
  

   size 
  ; 
  and, 
  at 
  last, 
  the 
  latter 
  eat 
  nearly 
  all 
  the 
  pulpy 
  parts 
  of 
  the 
  leaves, 
  

   leaving 
  little 
  more 
  than 
  the 
  midrib 
  and 
  vein^. 
  

  

  Upon 
  completing 
  their 
  growth, 
  they 
  either 
  crawl 
  down 
  the 
  tree 
  or 
  

   let 
  themselves 
  down 
  by 
  means 
  of 
  a 
  silken 
  thread, 
  and 
  burrow 
  into 
  the 
  

   ground. 
  Here, 
  at 
  a 
  depth 
  of 
  from 
  two 
  to 
  five 
  inches, 
  and 
  usually 
  

   within 
  a 
  radius 
  of 
  from 
  four 
  to 
  eight 
  feet 
  from 
  the 
  roots 
  of 
  the 
  tree, 
  

   they 
  form 
  their 
  cocoons, 
  within 
  two 
  or 
  three 
  days 
  after 
  completing 
  

   which 
  they 
  become 
  chrysalids. 
  

  

  Food-plants. 
  — 
  Packard 
  thinks 
  that 
  the 
  native 
  food-plant 
  of 
  this 
  

  

  