﻿386 
  W. 
  B. 
  JOHNSON 
  AND 
  LLEWELLYN 
  LLOYD. 
  

  

  to 
  the 
  presence 
  or 
  virtual 
  absence 
  of 
  game 
  and, 
  of 
  course, 
  other 
  large 
  wild 
  animals, 
  

   such 
  as 
  baboons, 
  an 
  interesting 
  difference 
  occurs, 
  which 
  is 
  too 
  pronounced 
  to 
  be 
  

   accidental. 
  The 
  nucleated 
  blood 
  in 
  tachinoides 
  is 
  more 
  than 
  twice 
  as 
  plentiful 
  where 
  

   game 
  animals 
  and 
  baboons 
  are 
  almost 
  totally 
  absent 
  as 
  where 
  these 
  are 
  present 
  in 
  

   some 
  quantity, 
  and 
  this 
  seems 
  to 
  indicate 
  a 
  preference 
  for 
  mammalian 
  blood 
  (see 
  

   Table 
  III). 
  With 
  palpalis, 
  a 
  fly 
  which 
  it 
  has 
  been 
  amply 
  proved 
  has 
  a 
  preference 
  

   for 
  reptiles 
  as 
  prey, 
  the 
  proportion 
  is 
  about 
  the 
  same 
  in 
  both 
  cases. 
  In 
  this 
  con- 
  

   nection 
  it 
  should 
  be 
  pointed 
  out 
  that 
  there 
  can 
  be 
  no 
  specially 
  large 
  numbers 
  of 
  

   Varanus, 
  the 
  only 
  large 
  reptile 
  concerned, 
  in 
  the 
  densely 
  populated 
  parts 
  as 
  opposed 
  

   to 
  the 
  less 
  populous 
  areas. 
  The 
  animal 
  is 
  much 
  esteemed 
  as 
  food 
  and 
  is 
  greatly 
  

   hunted, 
  and 
  the 
  only 
  reason 
  it 
  survives 
  in 
  the 
  densely 
  populated 
  districts 
  is 
  that 
  it 
  

   is 
  a 
  particularly 
  shy 
  elusive 
  creature. 
  

  

  (/) 
  Seasonal 
  Variation 
  in 
  Nutrition. 
  

  

  In 
  the 
  course 
  of 
  the 
  dissections 
  a 
  variation 
  in 
  the 
  gut 
  contents 
  of 
  the 
  flies 
  was 
  

   observed 
  which 
  could 
  be 
  correlated 
  with 
  the 
  season 
  of 
  the 
  year. 
  When 
  the 
  fly 
  

   contained 
  only 
  a 
  trace 
  of 
  detritus 
  in 
  the 
  gut 
  just 
  anterior 
  to 
  the 
  Malpighian 
  tubules, 
  

   it 
  was 
  considered 
  to 
  be 
  in 
  a 
  very 
  hungry 
  state. 
  Under 
  this 
  heading 
  recently 
  emerged 
  

   flies 
  which 
  had 
  not 
  fed 
  were 
  necessarily 
  included, 
  as 
  there 
  is 
  in 
  them 
  a 
  small 
  trace 
  

   of 
  detritus 
  in 
  this 
  position 
  and 
  the 
  gut 
  contents 
  in 
  only 
  two 
  or 
  three 
  cases 
  could 
  be 
  

   described 
  as 
  nil. 
  The 
  fact 
  that 
  the 
  data 
  are 
  collected 
  in 
  different 
  districts 
  rather 
  

   detracts 
  from 
  their 
  value, 
  but 
  the 
  records 
  from 
  the 
  nearest 
  Meteorological 
  Recording 
  

   Station 
  have 
  been 
  collected 
  for 
  the 
  various 
  months 
  and 
  are 
  given 
  in 
  Table 
  I. 
  The 
  

   record 
  begins 
  in 
  October 
  on 
  the 
  Niger 
  at 
  the 
  end 
  of 
  the 
  rains, 
  when 
  tornados 
  are 
  

   still 
  occurring 
  and 
  the 
  grass 
  is 
  high 
  and 
  green. 
  In 
  this 
  month 
  30 
  per 
  cent, 
  of 
  the 
  

   flies 
  examined 
  had 
  recently 
  fed, 
  " 
  recently 
  " 
  being 
  broadly 
  interpreted. 
  The 
  figures 
  

   for 
  November 
  were 
  obtained 
  in 
  Zaria 
  and 
  South 
  Kano 
  Provinces, 
  a 
  much 
  drier 
  part 
  

   of 
  the 
  country, 
  so 
  that 
  there 
  is 
  really 
  more 
  than 
  a 
  month's 
  interval 
  between 
  as 
  

   regards 
  the 
  state 
  of 
  the 
  season. 
  The 
  grass 
  was 
  dry 
  and 
  in 
  some 
  places 
  burnt, 
  while 
  

   the 
  undergrowth 
  in 
  the 
  forests 
  was 
  dying 
  down. 
  Of 
  the 
  flies 
  examined, 
  68 
  per 
  cent, 
  

   had 
  recently 
  fed. 
  In 
  the 
  next 
  month 
  near 
  the 
  same 
  locality, 
  much 
  of 
  the 
  grass 
  

   having 
  been 
  burnt 
  off, 
  the 
  percentage 
  rose 
  to 
  75 
  per 
  cent. 
  The 
  next 
  three 
  months' 
  

   figures 
  are 
  obtained 
  from 
  the 
  Benue 
  River 
  and 
  mid 
  Bauchi 
  Province 
  in 
  the 
  middle 
  

   and 
  late 
  dry 
  season, 
  when 
  the 
  grass 
  was 
  largely 
  burnt 
  off 
  and 
  the 
  undergrowth 
  had 
  

   died 
  down. 
  Breeding 
  was 
  known 
  to 
  be 
  actively 
  in 
  progress 
  and 
  many 
  young 
  flies 
  

   are 
  included 
  in 
  the 
  figures. 
  The 
  percentage 
  of 
  recently 
  fed 
  flies 
  are 
  : 
  January, 
  53 
  

   (from 
  a 
  very 
  small 
  total) 
  ; 
  February, 
  57 
  ; 
  March, 
  54. 
  The 
  figures 
  for 
  the 
  rest 
  of 
  

   the 
  twelve 
  months 
  are 
  taken 
  from 
  the 
  flies 
  caught 
  in 
  the 
  heavy 
  forest 
  area 
  at 
  Mashi- 
  

   washi, 
  where, 
  as 
  stated 
  above, 
  tachinoides 
  appeared 
  to 
  be 
  under 
  optimum 
  conditions. 
  

   In 
  April, 
  the 
  first 
  month 
  of 
  the 
  rains, 
  in 
  which 
  there 
  were 
  two 
  storms 
  only, 
  76 
  per 
  cent, 
  

   of 
  the 
  flies 
  examined 
  had 
  recently 
  fed. 
  At 
  this 
  time 
  the 
  floor 
  of 
  the 
  forest 
  was 
  still 
  

   very 
  open, 
  as 
  the 
  creepers 
  and 
  herbaceous 
  plants 
  were 
  just 
  beginning 
  to 
  sprout. 
  

   In 
  May, 
  the 
  figure 
  falls 
  rapidly 
  to 
  45 
  per 
  cent, 
  of 
  recently 
  fed 
  flies, 
  and 
  in 
  June 
  to 
  

   34 
  per 
  cent. 
  In 
  these 
  months 
  the 
  undergrowth 
  in 
  the 
  heavy 
  forest 
  was 
  becoming 
  

   denser, 
  especially 
  in 
  its 
  outskirts, 
  and 
  the 
  grass 
  along 
  its 
  edge 
  became 
  waist-high. 
  

   So 
  far 
  as 
  vegetation 
  was 
  concerned 
  the 
  conditions 
  near 
  the 
  Niger 
  in 
  October 
  were 
  

   being 
  approached. 
  Our 
  presence 
  seemed 
  to 
  disturb 
  the 
  fauna 
  in 
  the 
  forest 
  very 
  

   little, 
  and 
  there 
  was 
  still 
  abundant 
  spoor 
  of 
  bushbuck 
  and 
  red-flanked 
  duiker 
  there. 
  

   At 
  the 
  beginning 
  of 
  our 
  time 
  at 
  Mashiwashi 
  large 
  antelopes 
  visited 
  the 
  edge 
  of 
  the 
  

   heavy 
  forest 
  occasionally. 
  These 
  visits 
  ceased 
  in 
  May, 
  but 
  there 
  was 
  no 
  reason 
  for 
  

   them 
  to 
  continue, 
  as 
  conditions 
  were 
  then 
  better 
  for 
  these 
  animals 
  on 
  the 
  higher 
  

   ground. 
  

  

  We 
  obtained 
  no 
  evidence 
  that 
  the 
  flies 
  are 
  less 
  eager 
  to 
  feed 
  in 
  the 
  rainy 
  season 
  

   when 
  they 
  reach 
  a 
  host. 
  In 
  dull 
  weather 
  they 
  do 
  not 
  move 
  about 
  much 
  and 
  so 
  

  

  