﻿HIBERNATION. 
  39 
  

  

  Table 
  XIII. 
  — 
  Length 
  of 
  pre 
  pupal 
  and 
  pupal 
  stages, 
  El 
  Centra, 
  Cal., 
  1910. 
  

  

  Exp. 
  

   No. 
  

  

  Date 
  changed 
  to 
  prepupa. 
  

  

  Date 
  

  

  adult 
  

  

  emerged. 
  

  

  Length 
  

   period. 
  

  

  Average 
  

   mean 
  

  

  temper- 
  

   ature. 
  

  

  Aug. 
  19. 
  

   Aug. 
  22. 
  

   Sept. 
  6.. 
  

   Sept. 
  4.. 
  

   Sept. 
  7.. 
  

   Sept. 
  27. 
  

  

  Aug. 
  21 
  

   Aug. 
  24 
  

   Sept. 
  8 
  

   Sept. 
  8 
  

   Sept. 
  9 
  

   Sept. 
  29 
  

  

  Bays. 
  

   2£-3 
  

   2 
  

   2-21 
  

   3 
  

   2 
  

   2* 
  

  

  °F. 
  

  

  0) 
  

  

  C 
  1 
  ) 
  

  

  2 
  84.9 
  

   2 
  85.1 
  

   2 
  87.0 
  

   ( 
  ] 
  ) 
  

  

  Records 
  missing. 
  

  

  Temperature 
  at 
  Brawley, 
  U. 
  S. 
  Weather 
  Bureau. 
  

  

  In 
  the 
  Imperial 
  Valley 
  the 
  egg 
  stage 
  is 
  from 
  4i 
  to 
  5 
  clays, 
  the 
  

   larval 
  stage 
  from 
  4 
  to 
  5 
  days, 
  and 
  the 
  prepupal 
  and 
  pupal 
  stages 
  

   from 
  2 
  to 
  3 
  days, 
  making 
  the 
  total 
  life 
  cycle 
  only 
  10 
  to 
  12J 
  days 
  

   during 
  the 
  extreme 
  summer 
  temperature. 
  

  

  The 
  eggs 
  were 
  deposited 
  within 
  2 
  days 
  from 
  the 
  time 
  the 
  adult 
  

   females 
  emerged, 
  so 
  that 
  a 
  new 
  generation 
  might 
  occur 
  every 
  14 
  

   days 
  in 
  midsummer. 
  If 
  the 
  insect 
  emerges 
  from 
  hibernation 
  in 
  the 
  

   Imperial 
  Valley 
  at 
  the 
  same 
  time 
  as 
  in 
  Compton, 
  there 
  will 
  un- 
  

   doubtedly 
  be 
  1 
  generation 
  in 
  the 
  early 
  spring 
  occupying 
  30 
  to 
  40 
  

   days, 
  and 
  then 
  2 
  generations 
  a 
  month 
  for 
  5 
  or 
  6 
  months 
  and 
  1 
  

   longer 
  generation 
  in 
  the 
  fall, 
  or 
  12 
  to 
  14 
  generations 
  a 
  year. 
  Indeed, 
  

   with 
  such 
  rapid 
  multiplication 
  it 
  is 
  not 
  strange 
  that 
  crops 
  in 
  the 
  

   late 
  fall 
  become 
  seriouslv 
  infested. 
  

  

  SEASONAL 
  HISTORY 
  AT 
  TEMPE, 
  ARIZ. 
  

  

  Mr. 
  Wildermuth 
  during 
  October 
  and 
  November, 
  1911, 
  made 
  some 
  

   observations 
  on 
  the 
  life 
  cycle 
  of 
  this 
  thrips 
  at 
  Tempe. 
  These 
  gave 
  

   a 
  life 
  cycle 
  of 
  very 
  nearly 
  the 
  same 
  duration 
  as 
  in 
  the 
  Imperial 
  Valley 
  

   in 
  the 
  warm 
  weather, 
  but 
  in 
  November 
  the 
  cycle 
  was 
  lengthened 
  

   considerably. 
  He 
  found 
  that 
  specimens 
  collected 
  as 
  larvae 
  on 
  October 
  

   30 
  did 
  not 
  emerge 
  as 
  adults 
  until 
  December 
  1. 
  This 
  shows 
  the 
  same 
  

   effect 
  of 
  cooler 
  weather 
  on 
  this 
  insect 
  that 
  the 
  writer 
  observed 
  at 
  

   Compton, 
  Cal. 
  

  

  Taking 
  the 
  results 
  of 
  Mr. 
  Wildermuth's 
  and 
  the 
  writer's 
  observa- 
  

   tions 
  on 
  the 
  bean 
  thrips, 
  there 
  is 
  a 
  minimum 
  life 
  cycle 
  of 
  10 
  days 
  

   where 
  the 
  average 
  mean 
  temperature 
  is 
  about 
  88.75° 
  F., 
  and 
  a 
  maxi- 
  

   mum 
  of 
  about 
  73 
  days 
  with 
  an 
  average 
  mean 
  temperature 
  of 
  about 
  

   53.58° 
  F. 
  

  

  HIBERNATION. 
  

  

  This 
  insect 
  hibernates 
  as 
  an 
  adult 
  only, 
  through 
  most 
  of 
  its 
  dis- 
  

   tribution 
  at 
  least. 
  It 
  may 
  be 
  that 
  in 
  the 
  more 
  southern 
  portion- 
  of 
  

   its 
  range 
  it 
  breeds 
  continuously 
  throughout 
  the 
  year, 
  but 
  our 
  obser- 
  

   vations 
  in 
  these 
  localities 
  mentioned 
  have 
  failed 
  to 
  show 
  it. 
  

  

  