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  Morgan 
  (A. 
  C.) 
  & 
  Crumb 
  (S. 
  E.). 
  The 
  Tobacco 
  Splitworm. 
  — 
  

   Bull. 
  U.S. 
  Dept. 
  Agric, 
  Washington, 
  B.C., 
  no. 
  59, 
  19th 
  Jan. 
  1914, 
  

   7 
  pp. 
  [Reed. 
  14th 
  April 
  1914.] 
  

  

  The 
  tobacco 
  splitworm 
  [Phthorimaea 
  operculella, 
  Z.) 
  has 
  been 
  

   reported 
  as 
  having 
  done 
  serious 
  damage 
  to 
  the 
  potato 
  in 
  California. 
  

   The 
  variation 
  in 
  food 
  habits 
  had 
  created 
  the 
  suspicion 
  that 
  the 
  form 
  

   working 
  upon 
  potatoes 
  might 
  be 
  specifically 
  distinct 
  from 
  the 
  one 
  

   attacking 
  tobacco. 
  During 
  the 
  summer 
  of 
  1913 
  experiments 
  were 
  

   conducted 
  to 
  determine 
  this 
  point. 
  The 
  earlier 
  stages 
  of 
  the 
  two 
  types 
  

   differ 
  only 
  in 
  size 
  and 
  coloration. 
  By 
  transposing 
  the 
  food-plants 
  the 
  

   larvae 
  can 
  be 
  made 
  to 
  approach 
  each 
  other 
  in 
  colour, 
  and 
  this 
  character 
  

   is 
  therefore 
  scarcely 
  sufficient 
  to 
  justify 
  a 
  specific 
  separation. 
  The 
  

   difference 
  in 
  size 
  disappears 
  when 
  the 
  potato-tuber 
  moth 
  is 
  reared 
  on 
  

   other 
  plants. 
  In 
  the 
  United 
  States 
  the 
  species 
  occurs 
  in 
  California 
  

   and 
  southward 
  from 
  a 
  line 
  connecting 
  the 
  District 
  of 
  Columbia 
  and 
  

   Colorado, 
  including 
  Tenessee, 
  Virginia, 
  North 
  Carolina, 
  South 
  Carolina, 
  

   Florida 
  and 
  Texas. 
  The 
  known 
  range 
  also 
  includes 
  Cuba, 
  Costa 
  Rica, 
  

   Peru, 
  Hawaii, 
  Australia, 
  Tasmania, 
  New 
  Zealand, 
  Sumatra, 
  Transvaal, 
  

   Rhodesia, 
  Algeria, 
  and 
  Southern 
  Europe. 
  The 
  known 
  food-plants 
  of 
  

   Phthorimaea 
  operculella 
  include 
  Solanum 
  torvum, 
  S. 
  verbasdfolium, 
  

   jS. 
  carolinense, 
  S. 
  nigrum 
  {?), 
  egg-plant 
  (S. 
  Melongena) 
  potato, 
  tomato, 
  

   Physalis 
  peruviana, 
  Physalis 
  sp., 
  Physalodes 
  physalodes, 
  Datura 
  stramon- 
  

   ium, 
  and 
  tobacco. 
  The 
  larva 
  occurs 
  as 
  a 
  borer 
  and 
  also 
  as 
  a 
  leaf 
  miner, 
  

   the 
  former 
  probably 
  being 
  the 
  original 
  habit. 
  In 
  Cuba 
  and 
  the 
  United 
  

   States 
  the 
  insect 
  is 
  known 
  on 
  tobacco 
  as 
  a 
  leaf-miner 
  only. 
  A 
  boring 
  

   tendency 
  is 
  still 
  apparent, 
  however, 
  as 
  noted 
  by 
  Houser, 
  in 
  that 
  the 
  

   larva 
  usually 
  tunnels 
  the 
  midrib 
  or 
  a 
  vein 
  in 
  addition 
  to 
  mining 
  the 
  

   membrane 
  of 
  the 
  leaf. 
  Only 
  the 
  older 
  tobacco 
  leaves 
  are 
  affected, 
  

   unless 
  the 
  infestation 
  is 
  very 
  severe, 
  and 
  they 
  become 
  blotched, 
  the 
  

   tobacco 
  being 
  rendered 
  unfit 
  for 
  wrappers. 
  In 
  mining 
  the 
  leaf 
  the 
  

   larva 
  spins 
  a 
  tent 
  of 
  silk 
  and 
  under 
  this 
  consumes 
  the 
  parenchyma. 
  

   Eggs 
  are 
  deposited 
  singly 
  on 
  the 
  foliage 
  of 
  the 
  host 
  plant 
  and, 
  after 
  

   about 
  four 
  days, 
  the 
  larvae 
  emerge. 
  The 
  larva 
  is 
  very 
  active 
  and 
  

   continues 
  its 
  work 
  for 
  about 
  15 
  to 
  17 
  days, 
  after 
  which 
  it 
  pupates 
  in 
  

   a 
  tough 
  cocoon 
  of 
  silk 
  and 
  debris 
  in 
  the 
  clods 
  or 
  rubbish 
  at 
  or 
  near 
  

   the 
  surface 
  of 
  the 
  soil, 
  the 
  pupal 
  stage 
  lasting 
  from 
  six 
  to 
  nine 
  days. 
  

   Descriptions 
  are 
  given 
  of 
  the 
  various 
  stages 
  and 
  tables 
  showing 
  the 
  

   times 
  occupied 
  by 
  them. 
  Two 
  larval 
  parasites 
  are 
  recorded, 
  namely, 
  

   the 
  Braconid, 
  Chelonus 
  blacJcburni, 
  Cam., 
  and 
  the 
  Ichneumonid, 
  

   Limnerium 
  polynesiale, 
  Cam. 
  As 
  remedial 
  measures 
  Quaintance 
  

   recommends 
  pinching 
  the 
  larvae 
  in 
  the 
  leaves 
  and 
  the 
  destruction 
  of 
  

   all 
  trash 
  in 
  and 
  around 
  tobacco 
  fields 
  and 
  barns. 
  In 
  severe 
  infestations 
  

   it 
  may 
  be 
  necessary 
  to 
  prime 
  off 
  and 
  destroy 
  the 
  leaves 
  infested 
  by 
  

   the 
  earlier 
  generations. 
  It 
  is 
  also 
  well 
  to 
  transplant 
  the 
  crop 
  as 
  early 
  

   as 
  possible, 
  in 
  order 
  to 
  mature 
  it 
  before 
  the 
  appearance 
  of 
  the 
  most 
  

   destructive 
  generation 
  of 
  the 
  splitworm. 
  All 
  tobacco 
  stubble 
  should 
  

   be 
  destroyed 
  as 
  soon 
  as 
  the 
  crop 
  is 
  harvested, 
  to 
  prevent 
  the 
  breeding 
  

   of 
  a 
  hibernating 
  generation. 
  Potatoes 
  should 
  not 
  be 
  followed 
  by 
  

   tobacco, 
  for 
  the 
  infestation 
  of 
  tobacco 
  has 
  been 
  more 
  severe 
  in 
  such 
  

   cases, 
  than 
  where 
  a 
  different 
  rotation 
  was 
  followed. 
  Potatoes 
  and 
  

   tobacco 
  should 
  be 
  grown 
  as 
  far 
  apart 
  as 
  possible. 
  

  

  