﻿290 
  S. 
  A. 
  NEAVE. 
  

  

  In 
  the 
  case 
  of 
  many 
  species 
  the 
  larva 
  grows 
  very 
  slowly 
  after 
  hatching 
  and 
  

   often 
  takes 
  some 
  six 
  months 
  or 
  more 
  to 
  become 
  full-grown. 
  It 
  then, 
  especially 
  

   in 
  species 
  of 
  Tabanus, 
  goes 
  through 
  a 
  resting 
  period, 
  during 
  which 
  it 
  remains 
  

   buried 
  in 
  mud 
  or 
  sand, 
  sometimes 
  at 
  a 
  considerable 
  depth. 
  In 
  contrast 
  to 
  this 
  

   lengthy 
  larval 
  stage, 
  the 
  pupal 
  period 
  is 
  short, 
  varying, 
  in 
  my 
  experience, 
  from 
  

   10 
  to 
  16 
  or 
  18 
  days, 
  according 
  to 
  the 
  species 
  and 
  the 
  climatic 
  conditions, 
  the 
  longer 
  

   period 
  being 
  usual 
  for 
  the 
  larger 
  species 
  of 
  Tabanus. 
  

  

  One 
  difficulty 
  connected 
  with 
  the 
  question 
  of 
  these 
  flies 
  having 
  more 
  than 
  one 
  

   brood 
  per 
  annum 
  arises 
  from 
  the 
  fact 
  that 
  even 
  in 
  larvae 
  from 
  the 
  same 
  batch 
  of 
  

   eggs 
  the 
  rate 
  of 
  growth 
  is 
  extremely 
  variable, 
  and 
  consequently 
  the 
  processes 
  of 
  

   pupation 
  and 
  emergence 
  do 
  not 
  take 
  place 
  simultaneously 
  in 
  a 
  certain 
  proportion 
  

   of 
  the 
  individuals. 
  Some 
  of 
  the 
  remainder 
  take 
  longer 
  to 
  reach 
  maturity, 
  others 
  

   seem 
  to 
  pass 
  through 
  an 
  extended 
  dormant 
  period. 
  The 
  adults 
  arising 
  from 
  these 
  

   emerge 
  at 
  irregular 
  intervals, 
  often 
  months 
  later. 
  This 
  probably 
  explains 
  the 
  

   capture 
  of 
  odd 
  specimens 
  of 
  any 
  species 
  long 
  after 
  the 
  usual 
  season. 
  It 
  would 
  

   also 
  seem 
  not 
  improbable 
  that 
  individuals 
  which 
  miss 
  their 
  normal 
  season 
  for 
  

   pupation 
  in 
  some 
  circumstances 
  continue 
  in 
  the 
  larval 
  stage 
  until 
  the 
  following 
  

   year. 
  Thus 
  I 
  possessed 
  in 
  my 
  laboratory 
  in 
  January 
  and 
  February 
  examples 
  of 
  

   larvae 
  of 
  T. 
  corax, 
  some 
  still 
  in 
  a 
  dormant 
  state 
  and 
  others 
  not 
  yet 
  mature, 
  the 
  

   season 
  for 
  the 
  adult 
  flies 
  being 
  over 
  by 
  the 
  beginning 
  of 
  January. 
  It 
  would 
  appear 
  

   that 
  these 
  would 
  not 
  have 
  produced 
  imagines 
  until 
  the 
  following 
  December, 
  though 
  

   I 
  was 
  unable 
  to 
  decide 
  this 
  point 
  on 
  account 
  of 
  my 
  return 
  to 
  England. 
  

  

  The 
  problem 
  of 
  rearing 
  in 
  captivity 
  and, 
  still 
  more, 
  the 
  segregation 
  of 
  a 
  large 
  

   number 
  of 
  unidentified 
  species 
  of 
  Tabanid 
  larvae 
  was 
  no 
  easy 
  one. 
  The 
  larvae, 
  

   especially 
  of 
  the 
  larger 
  species, 
  are 
  astonishingly 
  strong 
  and 
  active, 
  and 
  in 
  spite 
  

   of 
  their 
  semi-aquatic 
  habits, 
  can 
  travel 
  considerable 
  distances 
  over 
  a 
  perfectly 
  dry 
  

   surface 
  without 
  apparent 
  inconvenience. 
  They 
  are 
  also 
  very 
  liable 
  to 
  wander, 
  

   chiefly 
  at 
  night, 
  and 
  it 
  is 
  probable 
  that 
  in 
  nature 
  they 
  come 
  to 
  the 
  surface 
  a 
  good 
  

   deal 
  at 
  this 
  time 
  to 
  search 
  for 
  food. 
  They 
  were 
  therefore 
  singularly 
  difficult 
  to 
  

   control 
  and 
  retain 
  in 
  their 
  respective 
  receptacles, 
  and 
  on 
  numerous 
  occasions 
  

   numbers 
  of 
  larvae 
  of 
  the 
  smaller 
  species 
  were 
  destroyed 
  by 
  vagrant 
  individuals 
  

   of 
  some 
  large 
  species 
  such 
  as 
  T. 
  corax. 
  On 
  the 
  whole 
  the 
  best 
  receptacles, 
  from 
  

   the 
  limited 
  choice 
  which 
  was 
  obtainable 
  locally, 
  consisted 
  of 
  small 
  basin-shaped 
  

   vessels 
  made 
  of 
  hard 
  clay 
  by 
  the 
  local 
  natives. 
  These 
  were 
  of 
  various 
  sizes, 
  from 
  

   6 
  inches 
  to 
  a 
  foot 
  in 
  diameter. 
  They 
  were 
  placed 
  separately 
  under 
  cages 
  made 
  

   of 
  mosquito 
  netting 
  on 
  a 
  wooden 
  framework. 
  The 
  larvae 
  were 
  recovered 
  for 
  

   examination 
  or 
  other 
  purposes 
  by 
  merely 
  washing 
  them 
  out 
  of 
  the 
  mud 
  or 
  sand 
  

   in 
  which 
  they 
  were 
  placed. 
  This, 
  of 
  course, 
  required 
  to 
  be 
  done 
  very 
  carefully 
  in 
  

   the 
  case 
  of 
  the 
  smaller 
  species. 
  Pupae 
  found 
  under 
  these 
  circumstances 
  should 
  

   be 
  separated 
  from 
  the 
  larvae, 
  which 
  might 
  injure 
  them. 
  They 
  should 
  be 
  placed 
  

   vertically 
  and 
  head 
  upwards 
  just 
  below 
  the 
  surface 
  of 
  the 
  mud 
  or 
  sand 
  in 
  separate 
  

   basins. 
  The 
  soil 
  in 
  which 
  the 
  pupae 
  are 
  kept, 
  should 
  be 
  considerably 
  drier 
  than 
  

   that 
  which 
  best 
  suits 
  the 
  larvae. 
  

  

  The 
  majority 
  of 
  the 
  larvae 
  obtained 
  were 
  already 
  half-grown 
  when 
  captured 
  

   and 
  the 
  necessity 
  of 
  providing 
  them 
  with 
  very 
  minute 
  forms 
  of 
  food 
  did 
  not 
  arise. 
  

   The 
  best 
  food 
  for 
  the 
  smaller 
  species 
  appeared 
  to 
  be 
  the 
  immature 
  larvae 
  of 
  

  

  