﻿— 
  I07 
  — 
  

  

  the 
  foliage 
  upon 
  which 
  they 
  are 
  feeding, 
  each 
  with 
  a 
  closely 
  webbed 
  

   inner 
  retreat 
  for 
  concealment. 
  A 
  single 
  leaf 
  or 
  an 
  entire 
  plant 
  may 
  

   thus 
  be 
  inclosed. 
  The 
  brown 
  pupa 
  of 
  the 
  native 
  web-worms 
  is 
  formed 
  

   in 
  an 
  elongate 
  cocoon 
  within 
  a 
  silken 
  tube 
  among 
  the 
  surface 
  debris 
  or 
  

   in 
  the 
  loose 
  earth 
  beneath 
  the 
  plant. 
  The 
  paler 
  pupa 
  of 
  the 
  imported 
  

   web-worm 
  is 
  inclosed 
  in 
  a 
  compact 
  white 
  silken 
  cocoon. 
  The 
  moths 
  

   of 
  these 
  species 
  are 
  small, 
  brownish, 
  buff, 
  or 
  gray, 
  with 
  broad 
  sub- 
  

   triangular 
  wings, 
  and 
  present 
  a 
  triangular 
  outline 
  when 
  at 
  rest. 
  The 
  

   species 
  seem 
  to 
  hibernate 
  in 
  the 
  cocoon, 
  either 
  as 
  larvse 
  or 
  pupae. 
  

   There 
  are 
  three 
  or 
  more 
  broods 
  in 
  a 
  year, 
  usually 
  becoming 
  more 
  

   destructive 
  as 
  the 
  season 
  progresses. 
  The 
  numerous 
  dipterous 
  and 
  

   hymenopterous 
  parasites 
  of 
  these 
  species, 
  together 
  with 
  their 
  other 
  

   enemies, 
  insect 
  and 
  vertebrate, 
  seem 
  under 
  ordinary 
  conditions 
  to 
  keep 
  

   them 
  well 
  in 
  check. 
  

  

  The 
  protective 
  web 
  spun 
  by 
  these 
  caterpillars 
  is 
  not 
  sufficiently 
  

   dense 
  to 
  repel 
  an 
  arsenical 
  spray, 
  and 
  they 
  are 
  consequently 
  easily 
  de- 
  

   stroyed 
  and 
  their 
  injuries 
  checked 
  if 
  action 
  is 
  prompt 
  and 
  vigorous. 
  

   Their 
  attack 
  in 
  the 
  beet 
  field 
  often 
  develops 
  very 
  rapidly, 
  and 
  must 
  

   receive 
  immediate 
  attention 
  if 
  serious 
  mischief 
  is 
  to 
  be 
  prevented. 
  If 
  

   beets 
  are 
  to 
  be 
  planted 
  on 
  land 
  previously 
  covered 
  with 
  pigweed, 
  purs- 
  

   lane, 
  or 
  lamb's-quarters, 
  it 
  has 
  been 
  found 
  useful 
  to 
  harrow 
  the 
  land 
  

   thoroughly 
  in 
  fall 
  to 
  uncover 
  the 
  hibernating 
  larvse 
  and 
  pupae 
  in 
  their 
  

   cocoons, 
  and 
  thus 
  to 
  expose 
  them 
  to 
  destruction 
  by 
  the 
  weather 
  and 
  

   their 
  natural 
  enemies. 
  

  

  Four 
  species 
  of 
  native 
  web-worms 
  have 
  been 
  observed 
  in 
  Nebraska, 
  

   where 
  these 
  insects 
  have 
  been 
  most 
  extensively 
  studied, 
  three 
  of 
  them 
  

   feeding 
  upon 
  beets 
  and 
  one 
  on 
  lamb's-quarters 
  and 
  hence 
  likely 
  to 
  feed 
  

   also 
  upon 
  the 
  beet. 
  Two 
  of 
  these 
  have 
  been 
  well 
  studied; 
  the 
  common 
  

   web-worm 
  (^Loxostege 
  siniilalis) 
  and 
  the 
  beet 
  web-worm 
  (Z. 
  sticticalis). 
  

   The 
  first 
  is 
  common 
  in 
  Illinois, 
  although 
  it 
  has 
  never 
  proven 
  very 
  

   destructive 
  here, 
  and 
  the 
  second 
  probably 
  occurs 
  in 
  the 
  state, 
  although 
  

   it 
  has 
  not 
  yet 
  been 
  noticed 
  here 
  to 
  our 
  knowledge. 
  Another 
  common 
  

   species 
  of 
  the 
  genus, 
  L. 
  chortalis, 
  occurs 
  also 
  in 
  Illinois, 
  and 
  may 
  quite 
  

   possibly 
  attack 
  the 
  beet. 
  The 
  larvae 
  of 
  similalis 
  and 
  sticticalis 
  are 
  easily 
  

   distinguished. 
  That 
  of 
  similalis 
  (Fig. 
  2)2n 
  ^) 
  varies 
  from 
  pale 
  yellowish 
  

   to 
  dusky, 
  with 
  symmetrically 
  placed 
  black 
  dots 
  on 
  each 
  segment, 
  and 
  

   with 
  a 
  pair 
  of 
  narrow 
  pale 
  lines 
  down 
  the 
  middle 
  of 
  the 
  back 
  and 
  one 
  

   such 
  on 
  each 
  side 
  of 
  the 
  body. 
  The 
  larva 
  of 
  sticticalis 
  (Fig. 
  35, 
  a) 
  is 
  

   darker, 
  the 
  dots 
  are 
  black 
  with 
  white 
  centers, 
  and 
  there 
  are 
  three 
  broad 
  

   dark 
  stripes 
  above. 
  The 
  larva 
  of 
  the 
  imported 
  web-worm 
  {^Hellida 
  

   undalis 
  — 
  Fig. 
  38, 
  b, 
  c) 
  is 
  yellowish 
  or 
  grayish, 
  with 
  five 
  well-marked 
  

   brownish 
  purple 
  stripes 
  above, 
  but 
  no 
  conspicuous 
  dots. 
  

  

  