﻿OF 
  THE 
  SOUTHERN 
  PROVINCES, 
  NIGERIA. 
  20£ 
  

  

  Pests 
  attacking 
  stems 
  and 
  cobs. 
  

  

  The 
  chief 
  of 
  these 
  was 
  a 
  dirty-grey 
  caterpillar, 
  the 
  larva 
  of 
  the 
  Noctuid 
  moth, 
  

   Sesamia 
  calamistis, 
  Hampson 
  (Plate 
  xvii, 
  fig. 
  1). 
  Another 
  species, 
  which 
  is 
  almost 
  

   equally 
  numerous, 
  is 
  the 
  larva 
  of 
  the 
  Pyrahd 
  moth, 
  Eldana 
  saccharina, 
  Walk. 
  

   (Plate 
  xvii, 
  fig. 
  2), 
  a 
  white 
  maggot-like 
  caterpillar 
  with 
  black 
  head 
  and 
  prothoracic 
  

   plate. 
  A 
  third 
  borer 
  found 
  occasionally 
  in 
  the 
  stems 
  was 
  the 
  larva 
  of 
  the 
  

   Noctuid, 
  Busseola 
  fusca, 
  Hampson 
  (Plate 
  xvii, 
  fig. 
  3), 
  which 
  is 
  one 
  of 
  the 
  principal 
  

   borers 
  in 
  maize 
  in 
  South 
  Africa. 
  The 
  effect 
  produced 
  by 
  these 
  borers 
  varied 
  with 
  

   the 
  age 
  of 
  the 
  plant. 
  Young 
  plants 
  withered 
  and 
  sometimes 
  died, 
  but 
  older 
  plants 
  

   survived, 
  though 
  they 
  showed 
  the 
  results 
  of 
  the 
  attack 
  by 
  their 
  stunted 
  growth 
  and 
  

   withered 
  appearance, 
  and 
  by 
  the 
  failure 
  of 
  the 
  cobs 
  to 
  develop 
  and 
  mature- 
  

   satisfactorily. 
  A 
  large 
  number 
  of 
  malformed 
  cobs 
  examined 
  at 
  Agege 
  showed 
  

   larvae, 
  pupae 
  or 
  pupa-cases 
  at 
  the 
  core. 
  

  

  When 
  plants 
  bearing 
  cobs 
  are 
  attacked 
  the 
  caterpillars 
  seem 
  to 
  prefer 
  the 
  cob 
  to 
  

   the 
  stem, 
  but 
  the 
  mode 
  of 
  attack 
  is 
  different 
  in 
  each 
  case. 
  Sesamia 
  usually 
  feeds 
  away 
  

   at 
  the 
  heart 
  of 
  the 
  cob, 
  not 
  as 
  a 
  rule 
  touching 
  the 
  seeds, 
  and 
  when 
  full-fed, 
  pupates 
  

   in 
  this 
  situation. 
  The 
  damage 
  done 
  to 
  the 
  seed 
  is 
  therefore 
  indirect. 
  Eldana, 
  on 
  

   the 
  other 
  hand, 
  prefers 
  to 
  eat 
  the 
  grains, 
  through 
  which 
  it 
  tunnels 
  here 
  and 
  there,, 
  

   pupating 
  eventually 
  in 
  a 
  white 
  silken 
  cocoon, 
  firmly 
  bound 
  up 
  in 
  the 
  seed, 
  though 
  such 
  

   cocoons 
  may 
  sometimes 
  be 
  found 
  between 
  the 
  layers 
  of 
  the 
  husk. 
  

  

  The 
  two 
  common 
  species, 
  Sesamia 
  and 
  Eldana 
  are 
  both 
  checked 
  by 
  a 
  Tachinid 
  fly, 
  

   which 
  was 
  especially 
  abundant 
  at 
  Agege, 
  though 
  its 
  influence 
  as 
  a 
  check 
  was 
  found 
  

   to 
  be 
  reduced 
  owing 
  to 
  its 
  being 
  itself 
  much 
  subject 
  to 
  attack 
  by 
  Chalcid 
  parasites 
  — 
  

   a 
  new 
  species 
  of 
  the 
  family 
  Encyrtidae. 
  A 
  fact 
  of 
  great 
  importance 
  is 
  that 
  these 
  two 
  

   larvae 
  were 
  to 
  be 
  found 
  even 
  in 
  maize 
  stems 
  left 
  standing 
  in 
  the 
  field 
  long 
  after 
  the 
  

   cobs 
  had 
  been 
  picked. 
  These 
  stems 
  often 
  possess 
  vitality 
  enough 
  to 
  put 
  out 
  new 
  

   green 
  shoots, 
  which 
  may 
  continue 
  to 
  grow 
  for 
  weeks 
  after 
  the 
  cobs 
  have 
  been 
  removed. 
  

   The 
  larvae 
  of 
  Sesamia 
  and 
  of 
  Busseola 
  were 
  also 
  found 
  as 
  borers 
  in 
  the 
  stems 
  of 
  the 
  

   coarse 
  grass 
  found 
  so 
  abundantly 
  in 
  the 
  Ibadan 
  district, 
  and 
  moths 
  from 
  larvae 
  in 
  

   the 
  grass 
  were 
  bred 
  out 
  in 
  the 
  laboratory. 
  

  

  The 
  bright 
  pink 
  larva 
  of 
  another 
  Noctuid 
  works 
  havoc 
  in 
  a 
  particularly 
  subtle 
  way, 
  

   by 
  feeding 
  just 
  inside 
  the 
  apex 
  of 
  the 
  cob 
  on 
  the 
  silk, 
  which 
  may 
  then 
  fall 
  out. 
  For- 
  

   tunately 
  its 
  attentions 
  were 
  not 
  limited 
  to 
  young 
  silks, 
  but 
  extended 
  also 
  to 
  older 
  ones, 
  

   in 
  which 
  case 
  as 
  the 
  seeds 
  were 
  already 
  fertilised 
  it 
  could 
  do 
  little 
  harm. 
  When 
  

   full-fed 
  these 
  caterpillars 
  spun 
  their 
  cocoons 
  in 
  the 
  remains 
  of 
  the 
  silk 
  and 
  these 
  were 
  

   readily 
  obtained 
  by 
  gently 
  pulling 
  the 
  silks, 
  which 
  then 
  usually 
  came 
  away 
  quite 
  

   easily 
  in 
  one's 
  hand. 
  These 
  larvae 
  are 
  frequently 
  parasited 
  by 
  Tachinidae, 
  the 
  

   pupae 
  of 
  which 
  were 
  often 
  found 
  in 
  the 
  cocoons, 
  but 
  the 
  Tachinid 
  pupae 
  in 
  turn 
  are 
  

   often 
  infested 
  with 
  Chalcids. 
  This 
  pest 
  was 
  much 
  more 
  abundant 
  in 
  Agege 
  than 
  in 
  

   the 
  Ibadan 
  district. 
  

  

  Towards 
  the 
  end 
  of 
  the 
  maize 
  season 
  a 
  further 
  caterpillar 
  pest, 
  the 
  larva 
  of 
  the 
  

   Pyralid 
  moth, 
  Mussidia 
  nigrivenella, 
  Rag. 
  (Plate 
  xvii, 
  fig. 
  5), 
  was 
  to 
  be 
  found 
  here 
  

   and 
  there 
  in 
  the 
  almost 
  ripe 
  cobs. 
  Some 
  importance 
  is 
  to 
  be 
  attached 
  to 
  it 
  in 
  the 
  

   field, 
  for 
  this 
  insect 
  is 
  one 
  of 
  the 
  chief 
  pests 
  attacking 
  stored 
  grain 
  and 
  is 
  indeed 
  

   responsible 
  for 
  almost 
  as 
  much 
  damage 
  as 
  the 
  various 
  grain 
  beetles, 
  infection 
  in 
  the 
  

   first 
  place 
  taking 
  place 
  in 
  the 
  field, 
  and 
  subsequent 
  generations 
  feeding 
  up 
  in 
  the 
  store. 
  

  

  