﻿OF 
  THE 
  SOUTHERN 
  PROVINCES, 
  NIGERIA. 
  199 
  

  

  Insects 
  attacking 
  the 
  Stem. 
  

  

  Two 
  species 
  of 
  scale-insects, 
  Hemichionaspis 
  minor, 
  Maskell, 
  and 
  Pulvinaria 
  

   jacksoni, 
  Newst. 
  (Plate 
  xxi, 
  fig. 
  1) 
  were 
  found 
  on 
  cotton 
  stems, 
  neither 
  in 
  any 
  great 
  

  

  Fig. 
  1. 
  Pseudagrilus 
  sophorae, 
  L. 
  

  

  abundance. 
  The 
  former, 
  a 
  small 
  insect 
  occurring 
  in 
  such 
  great 
  profusion 
  on 
  par- 
  

   ticular 
  plants 
  as 
  to 
  give 
  at 
  a 
  distance 
  the 
  impression 
  that 
  the 
  branches 
  might 
  have 
  

   been 
  dusted 
  with 
  a 
  white 
  powder, 
  was 
  frequently 
  found 
  also 
  on 
  a 
  fibre 
  plant, 
  Urena 
  

   lobata, 
  L., 
  on 
  okra 
  (Hibiscus 
  esculentus, 
  L.) 
  and 
  various 
  other 
  Malvaceae, 
  and 
  on 
  a 
  

   species 
  of 
  Ipomoea, 
  but, 
  as 
  the 
  season 
  went 
  on, 
  it 
  was 
  much 
  checked 
  by 
  both 
  larvae 
  

   and 
  imagos 
  of 
  a 
  CoccineUid 
  beetle, 
  Chilocorus 
  schiodtei, 
  Muls., 
  which 
  occurred 
  

   abundantly, 
  and 
  had 
  a 
  gregarious 
  tendency, 
  even 
  pupating 
  close 
  together. 
  The 
  

   Pulvinaria, 
  a 
  species 
  recorded 
  also 
  as 
  a 
  cotton 
  pest 
  in 
  Uganda, 
  was 
  much 
  less 
  numerous, 
  

   being 
  found 
  here 
  and 
  there 
  only 
  in 
  a 
  ten-acre 
  plot 
  of 
  Griffin 
  cotton. 
  

  

  The 
  larva 
  of 
  a 
  small 
  green 
  Buprestid 
  beetle, 
  Pseudagrilus 
  sophorae, 
  L., 
  (fig. 
  1) 
  caused 
  

   considerable 
  damage 
  and 
  some 
  loss 
  of 
  plants 
  owing 
  to 
  its 
  habit 
  of 
  boring 
  the 
  stems. 
  

   The 
  appearance 
  produced 
  in 
  the 
  plants 
  was 
  characteristic. 
  When 
  a 
  young 
  plant 
  

   was 
  attacked 
  general 
  stunting 
  and 
  distortion 
  with 
  shortening 
  of 
  the 
  internodes 
  was 
  

   produced, 
  and 
  the 
  uppermost 
  leaves 
  failed 
  to 
  attain 
  full 
  size, 
  though 
  the 
  lower 
  

   ones 
  were 
  to 
  all 
  intents 
  normal 
  in 
  this 
  respect 
  (Plate 
  xx). 
  Young 
  plants 
  attacked 
  

   did 
  not 
  as 
  a 
  rule 
  die, 
  but 
  often 
  went 
  on 
  to 
  produce 
  undersized 
  imperfect 
  bolls. 
  Older 
  

   plants 
  became 
  sickly 
  and 
  tended 
  to 
  shed 
  their 
  leaves. 
  On 
  examination 
  of 
  the 
  

   stem 
  of 
  such 
  a 
  plant 
  the 
  point 
  of 
  entrance 
  of 
  the 
  grub 
  could 
  usually 
  be 
  found 
  near 
  

   the 
  ground, 
  so 
  that 
  it 
  is 
  here, 
  in 
  all 
  probability, 
  that 
  the 
  parent 
  beetle 
  deposits 
  its 
  

   egg 
  ; 
  the 
  grub 
  then 
  bores 
  in 
  the 
  cambium 
  for 
  3 
  or 
  4 
  inches 
  to 
  and 
  fro 
  in 
  a 
  very 
  

   characteristic 
  zigzag 
  manner, 
  filling 
  up 
  the 
  tunnel 
  behind 
  itself 
  with 
  pink 
  sawdust- 
  

   like 
  excreta. 
  The 
  course 
  it 
  takes 
  in 
  the 
  cambium 
  explains 
  how 
  it 
  is 
  that 
  the 
  plants 
  

   do 
  not 
  die 
  as 
  a 
  result 
  of 
  the 
  attack 
  but 
  suffer 
  only 
  from 
  impairment 
  of 
  vitality. 
  The 
  

   larva 
  then 
  proceeds 
  to 
  tunnel 
  straight 
  up 
  in 
  the 
  wood 
  for 
  a 
  distance 
  of 
  about 
  12 
  inches, 
  

   usually 
  in 
  the 
  main 
  stem, 
  but 
  often 
  in 
  one 
  of 
  the 
  larger 
  limbs, 
  and 
  when 
  full-fed 
  

   penetrates 
  to 
  the 
  pith 
  cavity, 
  where 
  it 
  comfortably 
  pupates 
  in 
  a 
  little 
  bed 
  on 
  the 
  soft 
  

   pith, 
  though 
  occasionally 
  in 
  the 
  w 
  r 
  ood. 
  In 
  due 
  course 
  it 
  turns 
  into 
  a 
  beetle, 
  which 
  

   reaches 
  the 
  outer 
  world 
  by 
  boring, 
  such 
  holes 
  of 
  egress 
  being 
  readily 
  found 
  high 
  up 
  

   on 
  the 
  stem 
  of 
  the 
  plant. 
  

  

  No 
  method 
  of 
  coping 
  with 
  this 
  pest, 
  other 
  than 
  by 
  destruction 
  of 
  affected 
  plants, 
  

   was 
  devised. 
  Another 
  stem-borer 
  found 
  late 
  in 
  the 
  season 
  was 
  a 
  Lepidopterous 
  larva, 
  

   possibly 
  an 
  Aegeriid. 
  

   (C86) 
  a2 
  

  

  