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  THE 
  BEAN 
  THKIPS. 
  

  

  than 
  those 
  observed 
  by 
  the 
  writer. 
  This 
  may 
  have 
  been 
  due 
  to 
  the 
  

   higher 
  temperature 
  of 
  the 
  Imperial 
  Valley 
  and 
  vicinity, 
  where 
  his 
  

   observations 
  were 
  made. 
  Mr. 
  Wildermuth 
  noted 
  adults 
  in 
  copula- 
  

   tion 
  the 
  day 
  that 
  they 
  emerged, 
  and 
  oviposition 
  on 
  the 
  following 
  

   date. 
  He 
  also 
  observed 
  this 
  species 
  to 
  oviposit 
  during 
  the 
  entire 
  day, 
  

   whereas 
  the 
  writer 
  never 
  observed 
  it 
  to 
  oviposit 
  except 
  in 
  the 
  after- 
  

   noon 
  or 
  night. 
  

  

  PROPORTION 
  OF 
  THE 
  SEXES. 
  

  

  The 
  bean 
  thrips 
  was 
  under 
  the 
  observation 
  of 
  the 
  writer 
  for 
  a 
  

   period 
  of 
  more 
  than 
  two 
  years, 
  during 
  which 
  time 
  it 
  had 
  been 
  ob- 
  

   served 
  in 
  the 
  field 
  at 
  all 
  times 
  of 
  the 
  year. 
  In 
  all 
  observations 
  made 
  

   during 
  the 
  investigation 
  of 
  this 
  insect 
  the 
  males 
  and 
  females 
  were 
  

   collected 
  together 
  and 
  copulation 
  was 
  observed 
  from 
  early 
  in 
  Febru- 
  

   ary 
  until 
  reproduction 
  ceased 
  late 
  in 
  the 
  fall. 
  Apparently 
  the 
  

   females 
  outnumber 
  the 
  males, 
  but 
  this 
  may 
  be 
  due 
  to 
  the 
  fact 
  that 
  

   the 
  females 
  are 
  not 
  quite 
  so 
  active 
  as 
  the 
  males, 
  and 
  are 
  not 
  dis- 
  

   turbed 
  on 
  the 
  plants 
  when 
  examined. 
  On 
  June 
  9, 
  1911, 
  out 
  of 
  17 
  

   specimens 
  reared 
  in 
  the 
  laboratory 
  9 
  were 
  females 
  and 
  8 
  males. 
  July 
  

   17, 
  1911, 
  the 
  writer 
  examined 
  another 
  series 
  of 
  live 
  adults 
  that 
  were 
  

   reared 
  in 
  the 
  laboratory. 
  Out 
  of 
  106, 
  80 
  were 
  females 
  and 
  26 
  males. 
  

   A 
  third 
  series 
  of 
  reared 
  adults 
  was 
  examined 
  October 
  16, 
  1911, 
  and 
  

   out 
  of 
  44 
  adults 
  32 
  were 
  females 
  and 
  12 
  males. 
  Apparently 
  the 
  per- 
  

   centage 
  of 
  females 
  is 
  too 
  high 
  and 
  does 
  not 
  indicate 
  the 
  exact 
  rela- 
  

   tion 
  between 
  the 
  sexes. 
  

  

  KINDS 
  OF 
  REPRODUCTION. 
  

  

  In 
  all 
  observations 
  made 
  on 
  this 
  topic 
  reproduction 
  has 
  been 
  

   bisexual, 
  and 
  in 
  view 
  of 
  the 
  fact 
  that 
  males 
  were 
  observed 
  at 
  all 
  

   times 
  and 
  copulation 
  also 
  occurred 
  at 
  all 
  times 
  in 
  the 
  year 
  when 
  

   this 
  insect 
  was 
  active, 
  this 
  would 
  seem 
  to 
  be 
  the 
  usual 
  method. 
  How- 
  

   ever, 
  although 
  the 
  few 
  experiments 
  made 
  to 
  determine 
  whether 
  

   parthenogenesis 
  occurred 
  gave 
  negative 
  results, 
  in 
  view 
  of 
  the 
  pre- 
  

   ponderance 
  of 
  females 
  during 
  certain 
  parts 
  of 
  the 
  season 
  it 
  is 
  quite 
  

   probable 
  that 
  asexual 
  reproduction 
  may 
  occur. 
  It 
  would 
  seem 
  that 
  

   this 
  method 
  would 
  occur 
  under 
  certain 
  conditions, 
  especially 
  in 
  

   view 
  of 
  the 
  fact 
  that 
  the 
  greenhouse 
  thrips 
  {Heliothrips 
  hcemorrhoi- 
  

   dalis) 
  1 
  reproduces, 
  so 
  far 
  as 
  we 
  know, 
  asexually 
  only, 
  the 
  male 
  hav- 
  

   ing 
  never 
  been 
  discovered. 
  

  

  FEEDING 
  HABITS. 
  

  

  Both 
  the 
  adult 
  and 
  larva 
  of 
  this 
  thrips 
  injure 
  the 
  host 
  by 
  feeding 
  

   on 
  the 
  foliage. 
  As 
  in 
  the 
  case 
  of 
  the 
  greenhouse 
  thrips, 
  the 
  lower 
  

  

  i 
  " 
  The 
  Greenhouse 
  Thrips," 
  Bui. 
  64, 
  Bur. 
  Ent., 
  U. 
  S. 
  Dept. 
  Agr. 
  

  

  