﻿440 
  

  

  reported 
  as 
  doing 
  considerable 
  damage 
  in 
  parts 
  of 
  Orange 
  County, 
  

   visited 
  on 
  4th 
  and 
  5th 
  Feb., 
  and 
  later 
  at 
  Pasadena. 
  

  

  Warren 
  (E.). 
  The 
  Prickly 
  Pear 
  Pest. 
  — 
  Agric. 
  Jl. 
  Union 
  of 
  S. 
  Africa, 
  

   Pretoria, 
  vii, 
  no. 
  3, 
  March 
  1914, 
  pp. 
  387-391, 
  2 
  figs. 
  

  

  This 
  paper 
  deals 
  with 
  the 
  effect 
  of 
  the 
  cochineal 
  insect 
  (Dactylopius 
  

   coccus) 
  upon 
  the 
  prickly 
  pear. 
  This 
  plant 
  is 
  not 
  indigenous 
  to 
  South 
  

   Africa, 
  but 
  is 
  becoming 
  a 
  serious 
  problem 
  owing 
  to 
  its 
  abundance 
  

   and 
  disagreeable 
  spines. 
  A 
  Commission 
  appointed 
  by 
  the 
  Queens- 
  

   land 
  Government, 
  which 
  also 
  has 
  considered 
  this 
  plant 
  a 
  menace, 
  

   found 
  in 
  Ceylon 
  that 
  prickly 
  pear 
  plants 
  infested 
  with 
  cochineal 
  

   insects 
  became 
  sickly. 
  When 
  in 
  South 
  Africa, 
  this 
  Commission 
  gave 
  

   into 
  the 
  charge 
  of 
  the 
  Division 
  of 
  Entomology 
  at 
  Pretoria, 
  for 
  experi- 
  

   mental 
  purposes, 
  a 
  piece 
  of 
  stem 
  of 
  this 
  plant 
  infested 
  with 
  these 
  

   insects. 
  Experiments 
  with 
  these 
  were 
  carried 
  out 
  at 
  the 
  Natal 
  Museum 
  

   under 
  charge 
  of 
  Dr. 
  C. 
  Akerman. 
  

  

  There 
  are 
  two 
  species 
  of 
  prickly 
  pear 
  common 
  in 
  South 
  Africa, 
  a 
  

   thin-stemmed 
  long-spined 
  species 
  of 
  a 
  bright 
  green 
  colour, 
  Ojmntia 
  

   monocantha, 
  and 
  a 
  thick-stemmed 
  short-spined 
  species 
  of 
  a 
  pale 
  blue- 
  

   green 
  colour, 
  0. 
  tuna. 
  In 
  addition 
  to 
  these 
  wild 
  and 
  useless 
  species, 
  

   certain 
  spineless 
  varieties 
  of 
  0. 
  anacantha 
  and 
  0. 
  monada 
  are 
  grown 
  

   to 
  a 
  certain 
  extent 
  as 
  cattle 
  food 
  for 
  the 
  dry 
  season. 
  The 
  material 
  

   for 
  these 
  experiments 
  was 
  received 
  in 
  June 
  1913, 
  and 
  only 
  the 
  first 
  

   two 
  species 
  mentioned, 
  were 
  used 
  as 
  food-plants. 
  0. 
  tuna 
  gave 
  

   negative 
  results, 
  as 
  the 
  insects 
  would 
  not 
  settle, 
  and 
  died 
  after 
  two 
  

   days 
  wandering 
  ; 
  three 
  other 
  attempts 
  to 
  infest 
  it 
  meeting 
  with 
  the 
  

   same 
  result. 
  On 
  0. 
  monocantha 
  however 
  they 
  settled 
  down 
  and 
  

   completed 
  their 
  hfe-history. 
  There 
  is 
  no 
  metamorphosis, 
  and 
  develop- 
  

   ment 
  is 
  simply 
  a 
  matter 
  of 
  growth. 
  Young 
  individuals 
  can 
  crawl 
  

   some 
  distance 
  — 
  in 
  one 
  case 
  as 
  much 
  as 
  10 
  feet 
  — 
  and 
  on 
  emerging 
  from 
  

   the 
  envelope 
  of 
  the 
  parent 
  are 
  of 
  a 
  dark 
  brown 
  colour, 
  just 
  visible 
  

   to 
  the 
  naked 
  eye. 
  When 
  full 
  grown 
  the 
  insect 
  may 
  measure 
  J 
  inch 
  in 
  

   diameter. 
  The 
  young 
  grow 
  to 
  maturity 
  in 
  about 
  4 
  or 
  5 
  weeks 
  and 
  

   usually 
  settle 
  down 
  permanently 
  after 
  about 
  two 
  days. 
  For 
  about 
  8 
  

   weeks 
  the 
  cactus 
  stem 
  showed 
  no 
  other 
  symptoms 
  of 
  ill-health 
  than 
  to 
  

   become 
  yellow 
  in 
  patches 
  around 
  the 
  cochineal 
  insects, 
  but 
  after 
  about 
  

   9 
  weeks 
  the 
  plants 
  began 
  to 
  shrivel 
  quite 
  suddenly, 
  and 
  dried 
  up 
  in 
  a 
  

   very 
  short 
  time. 
  The 
  collapse 
  was 
  striking 
  and 
  appeared 
  to 
  indicate 
  a 
  

   poisonous 
  effect 
  of 
  the 
  Coccid. 
  Plants 
  growing 
  in 
  the 
  Museum 
  garden 
  

   were 
  next 
  tried, 
  with 
  the 
  same 
  results, 
  though 
  there 
  the 
  growth 
  of 
  the 
  

   insect 
  was 
  slower 
  than 
  in 
  the 
  laboratory. 
  In 
  August 
  1913, 
  vigorous 
  

   plants 
  in 
  two 
  different 
  locahties 
  near 
  Pietermaritzburg 
  were 
  infected 
  ; 
  

   the 
  insects 
  took 
  good 
  hold 
  on 
  the 
  plants 
  and 
  portions 
  of 
  these 
  at 
  the 
  

   time 
  the 
  author 
  wrote 
  (January 
  1914) 
  exhibited 
  marked 
  symptoms 
  of 
  

   ill-health. 
  It 
  is 
  considered 
  that 
  these 
  insects 
  may 
  be 
  of 
  use 
  in 
  keeping 
  

   theprickly 
  pear 
  within 
  bounds 
  ; 
  and 
  should 
  they 
  stand 
  the^vinter 
  and 
  no 
  

   enemy 
  arise, 
  might 
  become 
  so 
  abundant 
  as 
  to 
  exterminate 
  0. 
  mono- 
  

   cantha. 
  In 
  such 
  a 
  case, 
  in 
  districts 
  where 
  prickly 
  pears 
  are 
  grown 
  for 
  

   cattle, 
  a 
  variety 
  which 
  is 
  spineless 
  and 
  immune 
  to 
  the 
  cochineal 
  insect 
  

   would 
  be 
  necessary. 
  Probably 
  it 
  is 
  more 
  important 
  to 
  exterminate 
  

   the 
  long-spined 
  species 
  than 
  to 
  continue 
  to 
  grow 
  that 
  variety 
  for 
  

   cattle-food, 
  should 
  an 
  immune 
  variety 
  be 
  unobtainable. 
  

  

  