﻿696 
  

  

  of 
  wood-shavings, 
  about 
  8 
  inches 
  in 
  diameter, 
  is 
  placed 
  in 
  a 
  pail 
  and 
  

   from 
  3J 
  to 
  5 
  oz. 
  of 
  tobacco 
  juice 
  poured 
  over 
  it. 
  When 
  all 
  the 
  liquid 
  

   has 
  been 
  absorbed, 
  the 
  ball 
  is 
  put 
  in 
  a 
  basket 
  of 
  wire 
  gauze, 
  in 
  which 
  

   some 
  tow 
  has 
  first 
  been 
  placed. 
  A 
  piece 
  of 
  this 
  tow 
  is 
  pulled 
  out, 
  and 
  

   when 
  soaked 
  in 
  methylated 
  spirit, 
  is 
  used 
  as 
  a 
  wick. 
  The 
  basket 
  is 
  

   suspended 
  in 
  the 
  tree 
  and, 
  in 
  order 
  to 
  prevent 
  any 
  risk 
  of 
  fire, 
  a 
  piece 
  

   of 
  wire 
  gauze 
  is 
  placed 
  over 
  its 
  mouth 
  and 
  a 
  sheet 
  of 
  tin, 
  20 
  inches 
  

   square, 
  beneath 
  it. 
  Fumigation 
  is 
  then 
  carried 
  out 
  under 
  a 
  bag-like 
  

   tent 
  as 
  in 
  Chambaud's 
  system, 
  which 
  required 
  three 
  men, 
  one 
  being 
  

   constantly 
  engaged 
  in 
  attending 
  to 
  the 
  forge. 
  With 
  this 
  modification, 
  

   only 
  two 
  men 
  are 
  necessary. 
  With 
  one 
  cover 
  in 
  use 
  they 
  can 
  

   fumigate 
  from 
  five 
  to 
  six 
  trees 
  per 
  hour, 
  or 
  ten 
  trees, 
  if 
  two 
  covers 
  be 
  

   available. 
  The 
  material 
  for 
  the 
  cover 
  in 
  nicotin 
  fumigation 
  need 
  not 
  

   be 
  impermeable, 
  as 
  required 
  with 
  hydrocyanic 
  acid. 
  A 
  cover 
  of 
  

   suitable 
  material, 
  7 
  yards 
  square, 
  costs 
  about 
  £2 
  3s. 
  The 
  cost 
  per 
  

   tree 
  is 
  about 
  that 
  stated 
  by 
  Chambaud, 
  viz. 
  : 
  2d. 
  per 
  tree 
  if 
  one 
  

   cover 
  is 
  used, 
  or 
  l^d. 
  with 
  two 
  covers. 
  In 
  any 
  case, 
  it 
  is 
  important 
  

   to 
  fumigate 
  as 
  early 
  as 
  possible. 
  

  

  Some 
  apple 
  trees 
  at 
  the 
  Agricultural 
  School 
  of 
  Montpellier 
  had 
  

   purposely 
  been 
  left 
  unfumigated. 
  In 
  mid- 
  June 
  they 
  were 
  free 
  from 
  

   aphids, 
  owing 
  to 
  natural 
  control, 
  in 
  which 
  a 
  small 
  Hymenopterous 
  

   parasite 
  took 
  a 
  leading 
  part. 
  Where 
  parasites 
  are 
  known 
  to 
  be 
  present, 
  

   a 
  tree 
  might 
  be 
  set 
  apart 
  and 
  used 
  for 
  breeding 
  beneficial 
  insects 
  

   brought 
  from 
  other 
  trees. 
  Trioxys 
  auctus 
  and 
  Aphidius 
  crepidis 
  have 
  

   been 
  used 
  in 
  this 
  way 
  [see 
  this 
  Review, 
  Ser. 
  A, 
  ii, 
  pp. 
  620-621]. 
  

  

  Davis 
  (J. 
  J.). 
  The 
  Oat 
  Aphis. 
  — 
  U.S. 
  Dept. 
  Agric, 
  Washington, 
  B.C., 
  

   Bull. 
  no. 
  112, 
  21st 
  August 
  1914, 
  16 
  pp., 
  9 
  figs. 
  

  

  Aphis 
  avenae, 
  F., 
  is 
  second 
  in 
  importance 
  in 
  the 
  United 
  States 
  only 
  

   to 
  Toxoptera 
  graminum, 
  Rond. 
  ; 
  it 
  does 
  not 
  occur 
  in 
  such 
  abundance 
  

   as 
  that 
  species, 
  but 
  is 
  constantly 
  present 
  on 
  wheat, 
  occurring 
  at 
  the 
  

   base 
  of 
  the 
  plant 
  and 
  on 
  the 
  roots, 
  and 
  is 
  responsible 
  for 
  the 
  loss 
  of 
  

   thousands 
  of 
  bushels 
  annually. 
  The 
  distribution 
  of 
  A. 
  avenae 
  is 
  

   almost 
  world-wide, 
  and 
  it 
  occurs 
  in 
  all 
  parts 
  of 
  Europe, 
  and 
  in 
  most 
  of 
  

   the 
  United 
  States 
  except 
  the 
  Gulf 
  region. 
  A 
  description 
  of 
  the 
  various 
  

   forms, 
  the 
  winged 
  and 
  wingless 
  viviparous 
  female, 
  the 
  winged 
  male 
  

   and 
  the 
  wingless 
  oviparous 
  female, 
  is 
  given. 
  The 
  eggs 
  are 
  laid 
  in 
  the 
  

   axils 
  of 
  the 
  leaf 
  -buds 
  or 
  in 
  the 
  crevices 
  of 
  the 
  straw. 
  A. 
  avenae 
  may 
  

   be 
  distinguished 
  from 
  Macrosiphum 
  granarium, 
  Kirby, 
  T. 
  graminum, 
  

   A. 
  pomi, 
  de 
  G., 
  and 
  from 
  A. 
  sorbi, 
  Kalt., 
  by 
  the 
  pinkish, 
  orange 
  or 
  

   reddish 
  areas 
  on 
  the 
  abdomen, 
  at 
  the 
  bases 
  of 
  the 
  cornicles. 
  A 
  list, 
  

   stated 
  to 
  be 
  incomplete, 
  of 
  the 
  host 
  plants 
  of 
  this 
  Aphis 
  is 
  given. 
  

   These 
  are 
  largely 
  Gramineae, 
  including 
  Triticum, 
  Secale, 
  Avena, 
  

   Hordeum, 
  Phleum, 
  Poa, 
  Bromus, 
  Festuca, 
  Melica, 
  Andropogon, 
  Elymus, 
  

   Zea 
  ; 
  Typha 
  latifolia 
  is 
  recorded 
  as 
  a 
  host 
  for 
  A. 
  avenae 
  for 
  the 
  first 
  

   time 
  in 
  the 
  United 
  States. 
  Experiments 
  showed 
  that 
  this 
  aphid 
  

   would 
  not 
  breed 
  on 
  Muhlenbergia, 
  Agropyrum 
  occidentale, 
  Panicum 
  

   virgatum, 
  or 
  P. 
  bulbosum. 
  A. 
  avenae 
  is 
  usually 
  found 
  on 
  Triticum, 
  

   Carex, 
  Mains 
  and 
  Pyrus 
  in 
  autumn 
  and 
  spring, 
  on 
  Malus 
  and 
  Pyrus 
  

   before 
  June, 
  and 
  on 
  Avena, 
  Triticum 
  and 
  Carex 
  later 
  in 
  the 
  summer. 
  

   Many 
  of 
  the 
  early 
  records 
  of 
  infestation 
  of 
  A. 
  avenae 
  are 
  valueless 
  

   owing 
  to 
  confusion 
  in 
  identification. 
  Climate 
  is 
  an 
  important 
  factor 
  

  

  