﻿28 
  THE 
  BEAN 
  THRIPS. 
  

  

  OTHER 
  VEGETABLES. 
  

  

  During 
  the 
  spring 
  and 
  early 
  summer 
  this 
  insect 
  is 
  not 
  noticeable 
  

   on 
  either 
  the 
  sugar 
  or 
  table 
  beets. 
  Late 
  in 
  the 
  summer, 
  however, 
  as 
  

   the 
  wild 
  plants 
  die 
  down, 
  these 
  plants 
  often 
  become 
  badly 
  infested, 
  

   but 
  as 
  the 
  beets 
  have 
  nearly 
  completed 
  their 
  growth 
  little 
  real 
  in- 
  

   jury 
  results. 
  The 
  outside 
  leaves 
  seem 
  to 
  be 
  first 
  infested, 
  showing 
  

   series 
  of 
  minute 
  white 
  spots 
  more 
  or 
  less 
  in 
  chains, 
  where 
  the 
  chloro- 
  

   phyll 
  has 
  been 
  removed, 
  but 
  in 
  badly 
  infested 
  leaves 
  the 
  underside 
  

   becomes 
  white 
  and 
  dried 
  and 
  covered 
  with 
  small 
  black 
  spots, 
  causing 
  

   the 
  leaves 
  to 
  wilt. 
  Mr. 
  Parker 
  wrote 
  from 
  Hamilton 
  City, 
  Cal., 
  

   under 
  date 
  of 
  September 
  18, 
  1911, 
  that 
  the 
  injury 
  was 
  apparent 
  in 
  

   almost 
  every 
  field. 
  

  

  Cabbages 
  and 
  other 
  crucifers 
  are 
  commonly 
  infested 
  by 
  this 
  thrips 
  

   and 
  at 
  times 
  may 
  be 
  seriously 
  injured. 
  On 
  March 
  27, 
  1911, 
  cabbages 
  

   in 
  the 
  laboratory 
  yard 
  were 
  slightly 
  infested. 
  Where 
  they 
  had 
  fed 
  

   long 
  the 
  underside 
  of 
  the 
  leaf 
  was 
  fall 
  of 
  the 
  silvery- 
  white 
  feeding 
  

   marks 
  of 
  this 
  insect 
  and 
  the 
  tiny 
  black 
  specks 
  of 
  excrement. 
  Cauli- 
  

   flower 
  suffers 
  to 
  the 
  same 
  extent 
  as 
  the 
  less 
  valuable 
  cabbage. 
  

  

  This 
  insect 
  has 
  also 
  been 
  found 
  feeding 
  quite 
  extensively 
  on 
  let- 
  

   tuce, 
  potato, 
  and 
  tomato. 
  At 
  Hollywood, 
  Cal., 
  in 
  February, 
  1911, 
  

   it 
  was 
  very 
  abundant 
  on 
  the 
  foliage 
  of 
  pea 
  vines, 
  but 
  the 
  infestation 
  

   did 
  not 
  appear 
  to 
  increase, 
  probably 
  because 
  the 
  vines 
  were 
  quite 
  old. 
  

  

  PEAR. 
  

  

  Mr. 
  S. 
  W. 
  Foster 
  found 
  pear 
  foliage 
  badly 
  injured 
  on 
  August 
  31, 
  

   1909, 
  at 
  Martinez, 
  Cal. 
  He 
  wrote: 
  

  

  The 
  foliage 
  gave 
  the 
  appearance 
  from 
  a 
  distance 
  of 
  having 
  been 
  scalded. 
  

   Close 
  examination 
  showed 
  that 
  the 
  leaves 
  were 
  often 
  injured 
  in 
  large 
  areas 
  on 
  

   either 
  or 
  both 
  surfaces. 
  The 
  larvae, 
  feeding 
  only 
  on 
  these 
  outer 
  surfaces, 
  soon 
  

   cause 
  the 
  blackened 
  areas. 
  

  

  As 
  the 
  tree 
  has 
  made 
  most 
  of 
  its 
  growth 
  for 
  the 
  season 
  and 
  the 
  fruit 
  crop 
  

   has 
  been 
  harvested, 
  it 
  is 
  hardly 
  probable 
  that 
  this 
  species 
  will 
  prove 
  of 
  serious 
  

   consequence 
  to 
  the 
  growers 
  unless 
  it 
  should 
  get 
  so 
  numerous 
  as 
  to 
  appear 
  in 
  

   numbers 
  early 
  in 
  the 
  season. 
  

  

  ALFALFA. 
  

  

  The 
  following 
  field 
  observations 
  on 
  the 
  work 
  of 
  the 
  bean 
  thrips 
  

   on 
  alfalfa 
  and 
  cotton 
  were 
  made 
  by 
  Mr. 
  Wildermuth 
  in 
  the 
  Imperial 
  

   Valley, 
  Cal. 
  : 
  

  

  August 
  2, 
  1010. 
  This 
  thrips 
  does 
  nearly 
  all 
  if 
  not 
  all 
  of 
  its 
  feeding 
  on 
  the 
  

   upper 
  surface 
  of 
  the 
  leaf. 
  The 
  excrement 
  is 
  arranged 
  in 
  definite 
  rows, 
  often 
  

   semicircular 
  jn 
  form, 
  around 
  these 
  eaten 
  spots 
  and 
  makes 
  a 
  very 
  characteristic 
  

   mark 
  [see 
  fig. 
  9]. 
  The 
  eaten 
  spots 
  later 
  turn 
  yellow 
  and 
  then 
  the 
  alfalfa 
  

   presents 
  a 
  sickly 
  appearance. 
  August 
  4 
  I 
  visited 
  several 
  alfalfa 
  fields 
  and 
  all 
  

   were 
  very 
  much 
  injured 
  by 
  this 
  thrips. 
  Scarcely 
  a 
  leaf 
  could 
  be 
  found 
  that 
  

  

  