﻿16 
  THE 
  EED 
  SPIDER 
  ON 
  HOPS 
  IN 
  CALIFORNIA. 
  

  

  covered 
  and 
  often 
  connected 
  by 
  a 
  web 
  which 
  appeared 
  reddish-brown 
  

   or 
  silvery, 
  according 
  to 
  the 
  number 
  of 
  mites 
  present. 
  The 
  mites 
  were 
  

   frequently 
  found 
  clustered 
  like 
  swarms 
  of 
  bees 
  (PL 
  I, 
  figs. 
  1, 
  2), 
  and 
  

   the 
  lower 
  ones 
  in 
  dropping 
  off 
  were 
  blown 
  several 
  inches 
  by 
  the 
  wind. 
  

   That 
  migration 
  did 
  not 
  take 
  place 
  during 
  the 
  early 
  part 
  of 
  the 
  sea- 
  

   son 
  was 
  evidenced 
  by 
  the 
  fact 
  that 
  26 
  vines 
  which 
  were 
  planted 
  that 
  

   season 
  were 
  noted 
  to 
  be 
  free 
  from 
  mites 
  July 
  25, 
  1911, 
  while 
  the 
  sur- 
  

   rounding 
  older 
  vines 
  were 
  thoroughly 
  infested. 
  Soon 
  after 
  the 
  migra- 
  

   tions 
  commenced, 
  however, 
  mites 
  were 
  seen 
  upon 
  these 
  vines. 
  

  

  FOOD 
  PLANTS. 
  

  

  TetranycJius 
  bimaculatus 
  has 
  a 
  remarkably 
  large 
  number 
  of 
  host 
  

   plants, 
  and 
  as 
  will 
  be 
  seen 
  from 
  the 
  following 
  list, 
  these 
  plants 
  belong 
  

   to 
  a 
  wide 
  range 
  of 
  families, 
  including 
  glabrous 
  and 
  hirsute 
  plants. 
  

   For 
  convenience 
  the 
  following 
  list 
  has 
  been 
  divided 
  into 
  three 
  parts. 
  

   The 
  first 
  part 
  contains 
  a 
  list 
  of 
  greenhouse 
  and 
  ornamental 
  plants 
  

   attacked 
  by 
  the 
  mites; 
  the 
  second, 
  a 
  list 
  of 
  plants 
  attacked 
  in 
  the 
  field; 
  

   and 
  the 
  third, 
  a 
  list 
  of 
  plants 
  which 
  were 
  observed 
  to 
  be 
  infested 
  in 
  

   and 
  around 
  the 
  hopyards 
  in 
  the 
  Sacramento 
  Valley, 
  Cal. 
  

  

  List 
  of 
  food 
  plants 
  of 
  TetranycJius 
  bimaculatus. 
  

  

  Greenhouse 
  and 
  ornamental 
  plants 
  , 
  etc. 
  — 
  Rose, 
  violet, 
  carnation, 
  mignonette, 
  clematis, 
  

   pelargonium, 
  abutilon, 
  fuchsia, 
  passiflora, 
  manettia, 
  bouvardia, 
  feverfew, 
  verbena, 
  

   heliotrope, 
  honeysuckle, 
  hydrangea, 
  salvia, 
  morning-glory, 
  moonflower, 
  cypress 
  vine, 
  

   phlox, 
  aster, 
  chrysanthemum, 
  dahlia, 
  sunflower, 
  goldenglow 
  (Rudbechia 
  sp.), 
  calla, 
  

   Easter 
  lily, 
  Boston 
  smilax, 
  mimulus, 
  slipper 
  flower 
  (Calceolaria 
  sp.), 
  canary 
  bird 
  vine 
  

   (Tropseolum 
  peregrinum), 
  thunbergia, 
  wedding 
  bells 
  (Burgmansia 
  arborea), 
  castor-oil 
  

   bean, 
  Asparagus 
  plumosus, 
  cuphea, 
  godetia, 
  caladium, 
  tomato, 
  cucumber, 
  onion, 
  

   and 
  sweet 
  pea. 
  

  

  Field 
  plants, 
  shrubs, 
  and 
  trees. 
  — 
  Bean, 
  lima 
  bean, 
  cowpea, 
  pea, 
  cucumber, 
  chayote 
  

   (Sechium 
  edule), 
  cantaloupe, 
  watermelon, 
  squash, 
  celery, 
  eggplant, 
  pepper, 
  tomato, 
  

   pepino 
  (Solanum 
  muricatum), 
  cotton, 
  okra, 
  corn, 
  raspberry, 
  blackberry, 
  table 
  and 
  

   sugar 
  beets, 
  hops, 
  hemp, 
  alfalfa, 
  clover, 
  peanut, 
  groundnut 
  (Apios 
  apios), 
  English 
  ivy, 
  

   ferns, 
  privet, 
  hollyhock, 
  Kentucky 
  coffee 
  tree 
  (Gymnocladus 
  canadensis), 
  wistaria, 
  hop 
  

   tree 
  (Ptelea 
  trifoliata), 
  pecan, 
  ornamental 
  sassafras, 
  cedar, 
  arborvitae, 
  Colorado 
  blue 
  

   spruce, 
  maple, 
  horse-chestnut, 
  Carolina 
  poplar, 
  and 
  birch. 
  

  

  Host 
  plants 
  in 
  and 
  near 
  hopyards. 
  — 
  Mat-grass 
  (Lippia 
  nodifiora), 
  Amaranthus 
  blitoides, 
  

   hedge 
  mustard 
  (Sisymbrium 
  officinale), 
  wild 
  sunflower 
  (Helianthus 
  lenticularis) 
  , 
  alkali 
  

   mallow 
  (Disella 
  hederacea), 
  Persicaria 
  lapathiflora 
  (perennial 
  of 
  Persicaria), 
  rough 
  pig- 
  

   weed 
  (Amaranthus 
  retrofiexus), 
  prickly 
  lettuce 
  (Lactuca 
  scariola), 
  blessed 
  thistle 
  

   (Cnicus 
  benedictus), 
  alfalfa 
  (Medicago 
  sativa), 
  burdock 
  (Arctium 
  lappa), 
  burr 
  clover 
  

   (Medicago 
  hispida), 
  wild 
  morning-glory 
  (Convolvulus 
  sp.), 
  and 
  cheese 
  weed 
  (Malva 
  

   parviflora). 
  It 
  has 
  also 
  been 
  observed 
  on 
  Jamestown 
  or 
  Jimson 
  weed 
  (Datura 
  stra- 
  

   monium), 
  ironweed, 
  Jerusalem-oak 
  weed, 
  wild 
  geranium 
  (Geranium 
  memlatum), 
  and 
  

   Ligustrum 
  amurense. 
  

  

  From 
  the 
  foregoing 
  list 
  it 
  is 
  evident 
  that 
  this 
  mite 
  is 
  nearly 
  omniv- 
  

   orous 
  ' 
  so 
  far 
  as 
  plant 
  life 
  is 
  concerned, 
  and 
  without 
  doubt 
  there 
  are 
  

   many 
  other 
  food 
  plants 
  not 
  included 
  in 
  this 
  list. 
  

  

  i 
  It 
  is 
  more 
  than 
  likely, 
  since 
  its 
  feeding 
  habits 
  are 
  of 
  a 
  suctorial 
  nature, 
  that 
  this 
  mite 
  will 
  thrive 
  upon 
  

   nearly 
  any 
  form 
  of 
  vegetation 
  in 
  which 
  the 
  putescence 
  of 
  the 
  underside 
  of 
  the 
  leaf 
  is 
  not 
  so 
  heavy 
  or 
  luxuriant 
  

   as 
  to 
  prevent 
  its 
  direct 
  attack 
  upon 
  the 
  leaf 
  tissue 
  proper. 
  

  

  