﻿38 
  

  

  THE 
  BEAN 
  THRIPS. 
  

  

  Table 
  XI. 
  — 
  Length 
  of 
  incubation 
  of 
  the 
  eggs 
  of 
  the 
  bean 
  thrips, 
  El 
  Centro, 
  

  

  Gal., 
  1910. 
  

  

  

  Date 
  of 
  oviposition. 
  

  

  Number 
  

   laid. 
  

  

  Eggs 
  hatched. 
  

  

  Length 
  

   of 
  stage. 
  

  

  Average 
  

   mean 
  

  

  

  Date. 
  

  

  Number. 
  

  

  tempera- 
  

   ture. 
  

  

  July 
  27 
  

  

  2 
  

  

  ( 
  2 
  ) 
  

   ( 
  2 
  ) 
  

  

  Aug. 
  1 
  

   Aug. 
  15 
  

   Sept. 
  6 
  

  

  2 
  

   1 
  

  

  20 
  

  

  Days. 
  

   4J 
  

   4 
  

   5 
  

  

  °F. 
  

  

  0) 
  

  

  3 
  87.1 
  

  

  Aug. 
  11 
  

  

  Aug. 
  31 
  

  

  3 
  88. 
  7 
  

  

  

  

  

  1 
  Records 
  missing. 
  2 
  

   LARVAL 
  

  

  Many. 
  

   PERIOD. 
  

  

  3 
  

  

  At 
  Brawley. 
  

  

  

  The 
  active 
  feeding 
  larva 
  molts 
  once 
  before 
  its 
  final 
  molt 
  to 
  the 
  

   prepupal 
  stage. 
  This 
  occurs 
  in 
  from 
  one 
  and 
  one-half 
  to 
  two 
  days 
  

   after 
  it 
  hatches 
  from 
  the 
  egg. 
  The 
  larva 
  becomes 
  full 
  grown 
  and 
  

   changes 
  to 
  the 
  prepupa 
  in 
  from 
  four 
  and 
  one-half 
  to 
  five 
  days. 
  As 
  

   might 
  be 
  expected 
  from 
  the 
  great 
  difference 
  in 
  the 
  incubation 
  period 
  

   of 
  the 
  egg, 
  the 
  larval 
  period 
  in 
  the 
  Imperial 
  Valley, 
  as 
  observed 
  by 
  

   Mr. 
  Wildermuth, 
  is 
  much 
  shorter 
  than 
  at 
  Compton. 
  These 
  data 
  

   are 
  given 
  in 
  Table 
  XII. 
  

  

  Table 
  XII. 
  — 
  Length 
  of 
  larval 
  stage 
  of 
  the 
  bean 
  thrips 
  at 
  El 
  Centro, 
  Gal., 
  

  

  during 
  1910. 
  

  

  Exp. 
  

  

  No. 
  

  

  Eggs 
  hatched. 
  

  

  Molted. 
  

  

  Changed 
  to 
  

   prepupa. 
  

  

  Length. 
  

  

  Average 
  

   mean 
  

  

  temper- 
  

   ature. 
  

  

  Date. 
  

  

  Number. 
  

  

  Date. 
  

  

  Number. 
  

  

  Date. 
  

  

  Number. 
  

  

  1 
  

  

  

  1 
  

   3 
  

   1 
  

  

  1 
  

   1 
  

  

  Aug. 
  16 
  

   Aug. 
  19 
  

   Aug. 
  28 
  

   Sept. 
  3 
  

   Sept. 
  24 
  

  

  1 
  

   1 
  

  

  1 
  

   1 
  

   1 
  

  

  Aug. 
  19 
  

   Aug. 
  22 
  

   Aug. 
  31 
  

   Sept. 
  5 
  

   Sept. 
  27 
  

  

  

  Days. 
  

   4| 
  

   4i 
  

   51 
  

  

  4 
  

   5 
  

  

  °F. 
  

  

  85.8 
  

  

  2 
  

  

  Aug. 
  18 
  - 
  

  

  0) 
  

  

  3 
  

  

  Aug. 
  26 
  

  

  91.9 
  

  

  4 
  

  

  Sept. 
  1 
  

  

  89.7 
  

  

  5 
  

  

  Sept. 
  22 
  

  

  81.8 
  

  

  

  Total 
  

  

  

  

  7 
  

  

  5 
  

  

  5 
  

  

  

  

  

  

  

  

  

  1 
  Records 
  missing. 
  

   PREPUPAL 
  AND 
  PUPAL 
  PERIODS. 
  

  

  Unfortunately 
  Mr. 
  Wildermuth's 
  records 
  give 
  a 
  very 
  small 
  amount 
  

   of 
  data 
  on 
  the 
  length 
  of 
  the 
  prepupal 
  and 
  pupal 
  periods, 
  but 
  in 
  the 
  

   six 
  examples 
  observed 
  (see 
  Table 
  XIII) 
  the 
  stages 
  varied 
  from 
  2 
  

   to 
  3 
  daj's. 
  While 
  the 
  writer 
  was 
  studying 
  the 
  greenhouse 
  thrips 
  

   the 
  prepupal 
  stage 
  was 
  often 
  observed 
  to 
  last 
  only 
  a 
  few 
  hours, 
  and 
  

   tli 
  is 
  same 
  condition 
  probably 
  occurs 
  with 
  the 
  present 
  species 
  in 
  the 
  

   high 
  temperature 
  of 
  the 
  Imperial 
  Valley. 
  

  

  