﻿>5 
  THE 
  BEAN 
  THRIPS. 
  

  

  In 
  the 
  Imperial 
  Valley 
  the 
  life 
  history 
  of 
  the 
  bean 
  thrips 
  and 
  its 
  

   injuries 
  to 
  alfalfa 
  and 
  cotton 
  have 
  been 
  investigated 
  by 
  Mr. 
  V. 
  L. 
  

   Wildermuth, 
  of 
  this 
  bureau, 
  and 
  where 
  his 
  observations 
  are 
  used 
  

   credit 
  is 
  given 
  in 
  the 
  text. 
  1 
  Use 
  has 
  been 
  made 
  of 
  observations, 
  

   by 
  Messrs. 
  P. 
  R. 
  Jones 
  and 
  S. 
  W. 
  Foster, 
  of 
  this 
  bureau, 
  on 
  this 
  insect 
  

   in 
  the 
  more 
  northern 
  points 
  in 
  the 
  State. 
  Since 
  July, 
  1911, 
  the 
  writer 
  

   has 
  been 
  ably 
  assisted 
  by 
  Mr. 
  John 
  E. 
  Graf. 
  He 
  also 
  wishes 
  to 
  ex- 
  

   press 
  his 
  appreciation 
  to 
  Dr. 
  F. 
  II. 
  Chittenden, 
  under 
  whose 
  direc- 
  

   tions 
  he 
  has 
  conducted 
  the 
  investigation, 
  and 
  to 
  Prof. 
  F. 
  M. 
  Webster 
  

   for 
  the 
  free 
  use 
  of 
  notes 
  obtained 
  by 
  his 
  agents. 
  

  

  NATURE 
  AND 
  EXTENT 
  OF 
  INJURY. 
  

  

  The 
  damage 
  caused 
  by 
  the 
  bean 
  thrips 
  is 
  not 
  confined 
  to 
  the 
  foliage, 
  

   but 
  affects 
  as 
  well 
  the 
  fruit 
  and 
  stems 
  of 
  the 
  plant 
  attacked. 
  The 
  

  

  injury 
  is 
  caused 
  by 
  the 
  method 
  of 
  feeding. 
  

   Both 
  young 
  and 
  adults 
  obtain 
  their 
  food 
  by 
  

   puncturing 
  the 
  leaf 
  tissue 
  with 
  their 
  sharp 
  

   mouthparts 
  and, 
  after 
  lacerating 
  it, 
  with- 
  

   drawing 
  the 
  plant 
  juices 
  at 
  the 
  point 
  of 
  

   attack. 
  Figure 
  1, 
  although 
  a 
  drawing 
  of 
  a 
  

   different 
  species, 
  gives 
  an 
  idea 
  of 
  the 
  mouth- 
  

   parts 
  of 
  this 
  insect. 
  

  

  Each 
  time 
  as 
  the 
  contents 
  of 
  the 
  leaf 
  at 
  

   the 
  point 
  attacked 
  are 
  removed, 
  the 
  thrips 
  

   moves 
  to 
  a 
  new 
  point 
  and 
  repeats 
  the 
  opera- 
  

   tion, 
  so 
  that 
  if 
  the 
  insects 
  are 
  abundant 
  or 
  

   the 
  attack 
  is 
  long 
  continued 
  the 
  leaf 
  tissue 
  is 
  

   Fl 
  uoad*7f 
  S 
  a 
  e 
  thrip^ 
  showing 
  destroyed 
  over 
  the 
  entire 
  surface. 
  As 
  the 
  

   the 
  mouthparts. 
  Much 
  en- 
  supply 
  on 
  one 
  side 
  of 
  the 
  leaf 
  is 
  exhausted 
  

  

  larged. 
  (After 
  Moulton.) 
  ,, 
  \ 
  n 
  , 
  ,, 
  ,, 
  .,. 
  

  

  the 
  larva? 
  move 
  around 
  to 
  the 
  other, 
  or 
  11 
  

   adults 
  are 
  present 
  these 
  fly 
  or 
  jump 
  to 
  more 
  tender 
  leaves. 
  The 
  

   infested 
  and 
  badly 
  injured 
  leaves 
  turn 
  yellowish 
  or 
  white, 
  dry 
  up, 
  

   and 
  either 
  drop 
  off 
  or 
  hang 
  lifeless 
  to 
  the 
  plant. 
  Then, 
  as 
  the 
  

   attack 
  continues, 
  successive 
  leaves 
  are 
  attacked 
  until 
  in 
  extreme 
  

   cases 
  the 
  entire 
  plant 
  is 
  killed. 
  

  

  DESCRIPTION. 
  

  

  Heliothrips 
  fasciatus 
  belongs 
  to 
  the 
  Suborder 
  Terebrantia 
  and 
  the 
  

   Family 
  Thripidse 
  of 
  the 
  Order 
  Thysanoptera, 
  being 
  placed 
  in 
  this 
  

   position 
  because 
  of 
  the 
  downward-curved 
  ovipositor 
  of 
  the 
  female. 
  

   The 
  8-segmented 
  antennae, 
  with 
  the 
  last 
  segment 
  much 
  longer 
  than 
  

   the 
  7th, 
  and 
  the 
  reticulated 
  surface 
  of 
  the 
  body, 
  together 
  with 
  the 
  

   pointed 
  spines 
  on 
  the 
  wings, 
  place 
  this 
  insect 
  in 
  the 
  Genus 
  Helio- 
  

  

  1 
  Mr. 
  Wildermuth 
  studied 
  the 
  insect 
  in 
  its 
  relation 
  to 
  alfalfa, 
  without 
  knowing 
  that 
  it 
  

   was 
  being 
  investigated 
  by 
  the 
  author. 
  His 
  studies, 
  made 
  under 
  quite 
  different 
  climatic 
  

   conditions, 
  add 
  materially 
  to 
  the 
  value 
  of 
  the 
  results 
  obtained. 
  

  

  