﻿372 
  PROCEEDINGS 
  OF 
  THE 
  FOURTH 
  ENTOMOI 
  OGICAL 
  MEETING 
  

  

  produced 
  in 
  the 
  decaying 
  or 
  fermenting 
  vegetable 
  stuff 
  in 
  whicli 
  the 
  

   insects 
  have 
  been 
  found 
  to 
  breed, 
  all 
  these 
  smells 
  probably 
  represent 
  

   " 
  e<^g-laying 
  " 
  or 
  " 
  food 
  " 
  smells. 
  The 
  attraction 
  of 
  amyl 
  alcohol 
  for 
  

   a 
  small, 
  and 
  otherwise 
  rarely 
  seen, 
  Chloropid 
  fly 
  may 
  be 
  of 
  the 
  same 
  

   type, 
  as 
  is 
  also 
  the 
  attraction 
  of 
  skatol 
  for 
  females 
  of 
  Sarcophaga. 
  Flower 
  

   hauntinof 
  flies 
  seem 
  to 
  be, 
  as 
  might 
  be 
  expected, 
  comparatively 
  un- 
  

   specialized 
  in 
  their 
  tastes, 
  and 
  some 
  species, 
  e.g., 
  Rhyncomyia 
  and 
  

   Scatopse, 
  come 
  to 
  a 
  variety 
  of 
  sweet 
  smells. 
  A 
  small 
  Ceratopogonine 
  

   Chironomid 
  is 
  attracted 
  in 
  very 
  large 
  numbers 
  by 
  anethol 
  and 
  particular- 
  

   ly 
  by 
  anisaldehyde, 
  and 
  to 
  a 
  small 
  extent 
  by 
  a 
  few 
  other 
  aldehydes 
  ; 
  it 
  

   is 
  probable 
  that 
  we 
  have 
  here 
  to 
  do 
  with 
  an 
  insect 
  w^hich 
  is 
  more 
  or 
  less 
  

   specialized 
  with 
  regard 
  to 
  a 
  particular 
  plant. 
  As 
  both 
  sexes 
  are 
  attracted 
  

   it 
  is 
  not 
  a 
  case 
  of 
  mono-sexual 
  smell. 
  At 
  the 
  beginning 
  of 
  the 
  cold 
  

   weather 
  I 
  discovered 
  that 
  Thrips 
  was 
  strongly 
  attracted 
  by 
  two 
  aldehydes, 
  

   cinnamylaldehyde 
  and 
  benzaldehyde.* 
  These 
  experiments 
  I 
  propose 
  

   to 
  continue 
  when 
  Thrips 
  again 
  becomes 
  active 
  in 
  the 
  warm 
  weather, 
  

   and 
  the 
  investigation 
  may 
  produce 
  results 
  of 
  interest, 
  since 
  the 
  different 
  

   species 
  seem 
  to 
  show 
  different 
  degrees 
  of 
  specialization 
  in 
  their 
  choice 
  

   of 
  food 
  plants, 
  while 
  some 
  of 
  them, 
  such 
  as 
  the 
  tea,-Thrips, 
  are 
  pests 
  

   of 
  importance. 
  Moreover 
  there 
  are 
  three 
  or 
  four 
  other 
  substances, 
  

   which 
  to 
  us 
  have 
  almost 
  exactly 
  the 
  same 
  odour 
  as 
  benzaldehyde, 
  

   although 
  their 
  chemical 
  composition 
  is 
  by 
  no 
  means 
  the 
  same 
  : 
  by 
  

   experimenting 
  with 
  these 
  substances 
  it 
  may 
  be 
  possible 
  to 
  decide 
  how 
  

   far 
  the 
  olfactory 
  sense 
  of 
  Thrips 
  resembles 
  or 
  exceeds 
  our 
  own 
  in 
  delicacy 
  

   of 
  discrimination, 
  and 
  whether 
  or 
  not 
  the 
  attractiveness 
  depends 
  upon 
  

   the 
  presence 
  in 
  the 
  molecule 
  of 
  the 
  particular 
  group 
  of 
  atoms 
  character- 
  

   istic 
  of 
  the 
  aldehydes. 
  It 
  is 
  unusually 
  difficult 
  to 
  decide 
  the 
  sex 
  of 
  a 
  

   Thrips, 
  but 
  as 
  all 
  those 
  examined 
  seem 
  probably 
  to 
  be 
  females, 
  it 
  is 
  

   likely 
  that 
  this 
  is 
  also 
  a 
  case 
  of 
  a 
  food 
  or 
  egg-laying 
  smell, 
  and 
  not 
  a 
  

   sexual 
  guide. 
  . 
  

  

  With 
  regard 
  to 
  sexual 
  smells 
  Dr. 
  Coleman 
  of 
  Bangalore 
  recently 
  

   informed 
  me 
  that 
  he 
  had 
  performed 
  an 
  experiment 
  to 
  test 
  the 
  attractive- 
  

   ness 
  of 
  a 
  light 
  trap 
  for 
  females 
  of 
  the 
  destructive 
  " 
  Kumblihula 
  " 
  moths, 
  

   Amsacla 
  albistriga, 
  as 
  compared 
  with 
  the 
  attraction 
  of 
  the 
  pineapple 
  

   odour 
  (emitted 
  by 
  the 
  curious 
  caudal 
  tufts) 
  of 
  one 
  of 
  the 
  male 
  moths. 
  

   The 
  result 
  was 
  decisively 
  in 
  favour 
  of 
  the 
  male, 
  whose 
  charms 
  resulted 
  

   in 
  the 
  capture 
  of 
  nineteen 
  females 
  in 
  one 
  night. 
  This 
  direct 
  application 
  

   of 
  a 
  sexual 
  smell 
  is 
  of 
  very 
  great 
  interest 
  : 
  if 
  investigation 
  shows 
  that 
  

   the 
  attractive 
  substance 
  is 
  one 
  which 
  can 
  be 
  cheaply 
  procured, 
  {e.g., 
  

   a 
  simple 
  ester 
  such 
  as 
  amyl 
  acetate), 
  we 
  have 
  at 
  once 
  a 
  delightfully 
  

   easy 
  and 
  efficient 
  method 
  of 
  dealing 
  with 
  a 
  serious 
  pest. 
  

  

  *Joarn. 
  Eoo. 
  Biol. 
  IX. 
  1. 
  (March 
  1914.) 
  

  

  