﻿INSECTS 
  INJURIOUS 
  TO 
  CROPS 
  IN 
  ZANZIBAR. 
  151 
  

  

  Diptera. 
  

  

  Agromyza 
  sp. 
  The 
  larvae 
  of 
  this 
  fly 
  attack 
  the 
  young 
  green 
  seeds 
  in 
  the 
  pod, 
  

   making 
  a 
  ring 
  -like 
  track 
  around 
  the 
  seed 
  ; 
  the 
  pupae 
  are 
  formed 
  within 
  the 
  pod. 
  

  

  Ladies' 
  Fingers 
  (Hibiscus 
  esculentus). 
  

  

  These 
  useful 
  plants 
  harbour 
  a 
  number 
  of 
  important 
  insect 
  pests 
  of 
  which 
  the 
  

   following 
  have 
  been 
  recorded 
  : 
  — 
  Pectinophora 
  gossypiella, 
  Earias 
  insulana, 
  Sylepta 
  

   derogata 
  and 
  Prodenia 
  litura 
  ; 
  as 
  previously 
  mentioned 
  all 
  of 
  these 
  occur 
  on 
  cotton. 
  

  

  Nisotra 
  weisei, 
  Jac. 
  Numbers 
  of 
  these 
  small 
  flea-beetles 
  swarm 
  on 
  the 
  leaves, 
  

   giving 
  them 
  a 
  typical 
  shot-hole 
  appearance. 
  The 
  same 
  species 
  has 
  been 
  found 
  on 
  

   xoselle 
  (Hibiscus 
  sabdariffa). 
  

  

  Sweet 
  Potato 
  (Ipomoea 
  batatas). 
  

  

  Cyclas 
  formicarius, 
  F. 
  This 
  cosmopolitan 
  weevil 
  is 
  a 
  common 
  pest 
  throughout 
  

   ~fche 
  two 
  islands, 
  many 
  tubers 
  being 
  completely 
  riddled 
  and 
  destroyed. 
  All 
  instars 
  

   are 
  found 
  in 
  the 
  tubers. 
  

  

  Aspidomorpha 
  jnmcticosta, 
  Boh. 
  The 
  leaves 
  are 
  often 
  severely 
  attacked 
  by 
  the 
  

   larvae 
  of 
  this 
  Cassidid 
  beetle, 
  which 
  are 
  conspicuous 
  on 
  account 
  of 
  their 
  long 
  anal 
  

   process. 
  

  

  Cassava 
  (Manihot 
  utilissima). 
  

  

  This 
  useful 
  plant, 
  the 
  chief 
  food 
  supply 
  of 
  the 
  natives, 
  is 
  exceptionally 
  free 
  from 
  

   pests. 
  

  

  Pseudococcus 
  (Dactylopius) 
  virgatus 
  var. 
  madagascarensis, 
  Newst. 
  A 
  few 
  plants 
  have 
  

   been 
  observed 
  to 
  be 
  infested 
  with 
  this 
  Coccid. 
  

  

  Tetr 
  any 
  elms 
  sp. 
  This 
  small 
  red 
  mite 
  is 
  abundant 
  in 
  some 
  plots, 
  and 
  causes 
  

   wilting 
  and 
  curling 
  of 
  the 
  leaves. 
  

  

  INSECTS 
  INJURIOUS 
  TO 
  FRUIT 
  TREES. 
  

  

  Citrus. 
  

   Rhynchota. 
  

  

  Lepidosaphes 
  beckii, 
  Newman. 
  This 
  scale-insect 
  is 
  the 
  worst 
  enemy 
  of 
  Citrus, 
  

   and 
  in 
  many 
  plantations 
  the 
  trees 
  are 
  thickly 
  encrusted. 
  The 
  main 
  stem 
  and 
  laterals 
  

   are 
  the 
  favourite 
  sites, 
  but 
  leaves 
  and 
  fruit 
  are 
  also 
  attacked. 
  I 
  have 
  seen 
  numbers 
  

   of 
  oranges 
  packed 
  ready 
  for 
  export 
  infested 
  with 
  this 
  scale. 
  

  

  Icerya 
  purchasi, 
  Maskell. 
  Fortunately 
  very 
  few 
  trees 
  are 
  attacked 
  by 
  this 
  Coccid, 
  

   which 
  at 
  present 
  is 
  quite 
  a 
  minor 
  pest. 
  

  

  Icerya 
  seycliellarum, 
  Westw. 
  Has 
  been 
  observed 
  on 
  lemons. 
  

  

  Pseudococcus 
  obtusus, 
  Newst. 
  This 
  Coccid 
  has 
  been 
  taken 
  on 
  all 
  varieties 
  of 
  

   orange, 
  in 
  addition 
  to 
  its 
  other 
  food-plants. 
  

  

  Pseudococcus 
  citri, 
  Risso. 
  A 
  minor 
  pest 
  which 
  has 
  never 
  been 
  found 
  in 
  abundance. 
  

  

  Ceroplastes 
  rubens, 
  Maskell. 
  One 
  record 
  from 
  a 
  young 
  orange 
  tree. 
  

  

  Coccus 
  viridis, 
  L. 
  This 
  scale 
  is 
  very 
  prevalent 
  on 
  young 
  trees 
  in 
  some 
  plantations 
  

   -and 
  shows 
  a 
  marked 
  partiality 
  for 
  imported 
  species 
  of 
  Citrus. 
  

  

  