﻿202 
  History 
  of 
  Durham. 
  

  

  it 
  is 
  a 
  light 
  greenish 
  yellow. 
  It 
  has 
  a 
  longer 
  and 
  more 
  slen- 
  

   der 
  proboscis 
  than 
  the 
  species 
  that 
  prey 
  upon 
  other 
  insects; 
  

   otherwise 
  it 
  might 
  easily 
  be 
  confounded 
  with 
  them, 
  and 
  no 
  

   doubt 
  frequently 
  is. 
  It 
  also 
  lacks 
  the 
  thoracic 
  spines; 
  but 
  

   tiiese 
  are 
  very 
  variable 
  in 
  their 
  development, 
  and 
  not 
  always 
  

   a 
  safe 
  distinguishing 
  characteristic. 
  These 
  bugs 
  are 
  found 
  

   on 
  mulleins, 
  thistles, 
  and 
  other 
  weeds, 
  and 
  have 
  also 
  been 
  

   found 
  upon 
  tobacco 
  plants 
  in 
  several 
  localities, 
  feeding 
  upon 
  

   the 
  sap 
  of 
  the 
  leaves, 
  but 
  it 
  is 
  doubtful 
  whether 
  any 
  great 
  

   injury 
  can 
  be 
  charged 
  to 
  their 
  account. 
  The 
  ordinary 
  ob- 
  

   server 
  is 
  apt 
  to 
  mistake 
  the 
  purpose 
  for 
  which 
  many 
  insects 
  

   visit 
  various 
  plants. 
  The 
  spined 
  tree-bug 
  {Podisus 
  spinosus), 
  

   the 
  large 
  tree-bug 
  {Podisus 
  cynicus), 
  the 
  Stiretrus 
  diana 
  (a 
  

   plant 
  bug 
  of 
  a 
  purple-black 
  color, 
  with 
  red 
  or 
  orange 
  marks 
  

   on 
  the 
  thorax 
  and 
  scutellum), 
  and 
  the 
  Stiretrus 
  fimbriatus, 
  

   the 
  ground 
  colors 
  of 
  which 
  are 
  orange 
  or 
  yellow, 
  with 
  black 
  

   markings, 
  are 
  sometimes 
  found 
  upon 
  or 
  in 
  the 
  immediate 
  

   neighborhood 
  of 
  tobacco 
  plants. 
  These 
  bugs 
  should 
  not 
  be 
  

   destroyed, 
  unless 
  upon 
  careful 
  examination 
  they 
  are 
  found 
  

   actually 
  feeding 
  upon 
  the 
  juices 
  of 
  the 
  leaves, 
  as 
  it 
  is 
  more 
  

   than 
  probable 
  that 
  their 
  presence 
  is 
  beneficial, 
  rather 
  than 
  

   injurious. 
  

  

  From 
  the 
  early 
  part 
  of 
  June 
  until 
  the 
  sharp 
  frosts 
  destroy 
  

   their 
  food 
  in 
  the 
  fall, 
  the 
  larvae 
  of 
  the 
  sphinx 
  moths 
  infest 
  

   the 
  tobacco. 
  In 
  Virginia, 
  Maryland, 
  Kentucky, 
  Tennessee, 
  

   and 
  Missouri 
  both 
  the 
  SpJtinx 
  Carolina 
  and 
  the 
  Sphinx 
  quin- 
  

   quemaculata 
  are 
  found, 
  and 
  they 
  are 
  both 
  reported 
  as 
  found 
  

   in 
  the 
  tobacco 
  fields 
  as 
  far 
  north 
  as 
  latitude 
  41° 
  30'. 
  South 
  

   of 
  latitude 
  35° 
  only 
  the 
  Sphijix 
  ca7^o^ma 
  has 
  been 
  observed. 
  The 
  

   larvae 
  of 
  these 
  two 
  Sphingidoe 
  are 
  so 
  well 
  known 
  to 
  all 
  tobacco 
  

   growers 
  as 
  to 
  need 
  no 
  description 
  here. 
  They 
  have 
  always 
  

   been 
  regarded 
  as 
  the 
  most 
  inveterate 
  enemies 
  ol 
  the 
  to- 
  

   bacco 
  plant, 
  and, 
  despite 
  plans 
  adopted 
  for 
  their 
  destruc- 
  

   tion, 
  the 
  horn-worms 
  seem 
  to 
  be 
  as 
  numerous 
  as 
  ever. 
  

   In 
  some 
  seasons 
  there 
  are 
  comparatively 
  few 
  in 
  certain 
  

   localities, 
  but 
  it 
  has 
  been 
  noticed 
  that 
  the 
  fields 
  of 
  such 
  

   districts 
  are 
  often 
  visited 
  late 
  in 
  July 
  or 
  August 
  of 
  the 
  

   next 
  year 
  by 
  a 
  "heavy 
  shower" 
  of 
  horn-worms. 
  Com- 
  

   parative 
  immunity 
  for 
  one 
  season 
  too 
  often 
  causes 
  the 
  

   farmer 
  to 
  neglect 
  the 
  destruction 
  of 
  the 
  late 
  brood 
  of 
  

   worms 
  left 
  upon 
  the 
  suckers 
  which 
  spring 
  up 
  after 
  the 
  crop 
  

   is 
  harvested, 
  large 
  numbers 
  punating'and 
  hibernating, 
  pro- 
  

   tected 
  by 
  the 
  forgotten 
  and 
  neglected 
  trash 
  of 
  the 
  tobacco 
  

  

  