﻿OCCURRENCE 
  OF 
  LEAF-EATING 
  SAWFLIES 
  ON 
  CEREALS 
  IN 
  BRITAIN. 
  269 
  

  

  It 
  has 
  so 
  far 
  been 
  impossible 
  to 
  observe 
  the 
  oviposition 
  in 
  Pachynematus 
  owing 
  to 
  

   the 
  rapid 
  death 
  in 
  captivity 
  of 
  the 
  insects. 
  

  

  The 
  young 
  larvae 
  were 
  2-5 
  mm. 
  long 
  and 
  resembled 
  the 
  adults 
  in 
  coloration, 
  

   being 
  dark 
  brown 
  or 
  nearly 
  black 
  along 
  the 
  back, 
  with 
  the 
  lower 
  part 
  of 
  the 
  sides 
  and 
  

   the 
  underside 
  very 
  pale, 
  dull 
  cream 
  ; 
  the 
  vertex 
  and 
  eyes 
  are 
  black, 
  the 
  rest 
  of 
  the 
  

   head 
  pale. 
  Full-grown 
  larvae 
  measure 
  17 
  mm. 
  to 
  19 
  mm. 
  

  

  In 
  addition 
  to 
  wheat 
  and 
  oats 
  the 
  larvae 
  have 
  been 
  found 
  on 
  Arrhenatherum 
  

   avenaceum 
  (3), 
  and 
  Cameron, 
  who 
  figures 
  and 
  briefly 
  describes 
  the 
  larva, 
  states 
  that 
  

   it 
  feeds 
  on 
  Jttncus 
  effusus 
  and 
  other 
  species 
  of 
  J 
  uncus 
  and 
  on 
  Scirpus 
  lacustris 
  (4). 
  

  

  No 
  larvae 
  of 
  Pachynematus 
  under 
  8 
  mm. 
  have 
  been 
  observed, 
  when 
  the 
  coloration 
  

   corresponds 
  with 
  the 
  adult 
  of 
  16-18 
  mm. 
  Just 
  before 
  pupating 
  there 
  is 
  a 
  slight 
  colour 
  

   change 
  to 
  a 
  uniform 
  green. 
  In 
  addition 
  to 
  wheat 
  and 
  oats, 
  Poa 
  trivialis 
  (3), 
  P. 
  annua, 
  

   Car 
  ex 
  acuta 
  and 
  other 
  species 
  of 
  Car 
  ex 
  and 
  grasses 
  are 
  eaten 
  (4). 
  Cameron 
  gives 
  a 
  full 
  

   description 
  of 
  the 
  larva, 
  with 
  a 
  figure, 
  and 
  states 
  that 
  it 
  is 
  dimorphic. 
  The 
  larvae 
  of 
  

   both 
  species 
  lie 
  almost 
  motionless 
  along 
  the 
  leaf-blades, 
  although 
  Pachynematus 
  

   when 
  alarmed 
  is 
  sometimes 
  quite 
  active. 
  

  

  Mature 
  Dolcrus 
  larvae 
  make 
  no 
  cocoon 
  in 
  the 
  soil 
  for 
  pupation, 
  but 
  Pachynematus 
  

   spins 
  a 
  thin 
  brown 
  cocoon. 
  Cameron 
  obtained 
  cocoons 
  in 
  confinement 
  on 
  the 
  leaves 
  

   of 
  the 
  food-plants, 
  but 
  the 
  writer 
  was 
  unable 
  to 
  do 
  so 
  ; 
  the 
  larvae 
  simply 
  remained 
  

   inert 
  during 
  the 
  winter 
  and 
  died 
  in 
  the 
  early 
  spring. 
  The 
  adults 
  of 
  both 
  Dolerus 
  and 
  

   Pachynematus 
  are 
  common 
  and 
  apparently 
  generally 
  distributed. 
  Both 
  are 
  fully 
  

   described 
  by 
  Cameron, 
  the 
  latter 
  under 
  the 
  name 
  Nematus 
  capreae. 
  The 
  amount 
  

   of 
  damage 
  done 
  by 
  these 
  species 
  is 
  slight, 
  but 
  they 
  have 
  regularly 
  appeared 
  during 
  

   five 
  seasons 
  in 
  different 
  fields 
  in 
  the 
  Newport 
  district. 
  

  

  References. 
  

  

  1. 
  Sanderson, 
  " 
  Insects 
  Injurious 
  to 
  Staple 
  Crops." 
  

  

  2. 
  Riley 
  & 
  Marlatt, 
  " 
  Wheat 
  and 
  Grass 
  Sawflies," 
  Insect 
  Life, 
  vol. 
  iv. 
  

  

  3. 
  Miles, 
  " 
  Relation 
  of 
  Grass 
  Insects 
  to 
  Cultivated 
  Crops," 
  Annals 
  of 
  Applied 
  

  

  Biology, 
  vol. 
  viii, 
  nos. 
  3, 
  4. 
  

  

  4. 
  Cameron, 
  " 
  Monograph 
  of 
  the 
  British 
  Phytophagous 
  Hymenoptera," 
  vols, 
  i 
  and 
  ii. 
  

  

  