﻿HABITS. 
  15 
  

  

  In 
  the 
  case 
  of 
  soil, 
  the 
  lumps 
  and 
  sand 
  interfered 
  greatly 
  with 
  prog- 
  

   ress 
  and 
  were 
  responsible 
  for 
  many 
  changes 
  in 
  direction. 
  The 
  dis- 
  

   tance 
  gained 
  by 
  these 
  mites 
  in 
  10 
  hours 
  varied 
  greatly, 
  approximat- 
  

   ing 
  1 
  to 
  60 
  feet 
  from 
  the 
  starting 
  point. 
  The 
  actual 
  distance 
  traveled 
  

   over 
  soil 
  may 
  in 
  some 
  cases 
  exceed 
  the 
  above 
  where 
  the 
  soil 
  is 
  very 
  

   smooth 
  and 
  hard, 
  but 
  on 
  rough 
  ground 
  is 
  probably 
  much 
  less. 
  

  

  From 
  the 
  foregoing 
  experiments 
  it 
  seems 
  probable 
  that 
  the 
  mites 
  can 
  

   travel 
  some 
  distance 
  over 
  the 
  bare 
  soil, 
  thus 
  infesting 
  plants 
  more 
  or 
  

   less 
  widely 
  removed 
  from 
  those 
  on 
  which 
  they 
  passed 
  the 
  winter. 
  

  

  EMERGENCE 
  FROM 
  HIBERNATION. 
  

  

  First 
  appearance 
  of 
  mites 
  on 
  hops. 
  — 
  The 
  hop 
  vines 
  in 
  yards 
  that 
  were 
  

   known 
  to 
  be 
  infested 
  during 
  1910 
  were 
  frequently 
  inspected 
  for 
  mites 
  

   during 
  the 
  following 
  spring. 
  The 
  first 
  mite 
  observed 
  upon 
  a 
  hopvine 
  

   was 
  found 
  April 
  21 
  in 
  the 
  center 
  of 
  a 
  yard 
  near 
  Sacramento. 
  This 
  

   lone 
  mite 
  was 
  surrounded 
  by 
  eight 
  eggs 
  and 
  protected 
  by 
  a 
  small 
  

   amount 
  of 
  dusty 
  web. 
  No 
  more 
  mites 
  were 
  observed 
  until 
  May 
  9, 
  

   when 
  a 
  single 
  mite 
  was 
  discovered 
  on 
  a 
  hopvine 
  situated 
  100 
  feet 
  from 
  

   a 
  fence 
  dividing 
  two 
  large 
  hopyards 
  near 
  Perkins, 
  Cal. 
  Mites 
  were 
  

   later 
  found 
  upon 
  some 
  early 
  hops 
  which 
  were 
  growing 
  along 
  a 
  fence 
  

   and 
  were 
  also 
  present 
  in 
  about 
  the 
  same 
  numbers 
  upon 
  hopvines 
  some 
  

   distance 
  from 
  the 
  borders 
  of 
  the 
  hopyards. 
  The 
  mites 
  gradually 
  

   increased 
  in 
  numbers, 
  and 
  by 
  June 
  1 
  occasional 
  hopvines 
  were 
  found 
  

   on 
  which 
  the 
  lower 
  leaves 
  harbored 
  from 
  5 
  to 
  33 
  mites 
  each. 
  

  

  As 
  is 
  shown 
  by 
  the 
  foregoing 
  data, 
  the 
  mites 
  appeared 
  simultane- 
  

   ously 
  in 
  various 
  parts 
  of 
  the 
  hop 
  fields 
  and 
  did 
  not, 
  as 
  was 
  formerly 
  

   supposed, 
  invade 
  the 
  yards 
  from 
  along 
  the 
  edges 
  and 
  work 
  toward 
  the 
  

   center 
  of 
  the 
  fields. 
  

  

  MIGRATORY 
  ACTIVITIES. 
  

  

  Before 
  the 
  infestation 
  became 
  severe 
  the 
  mites 
  were 
  observed 
  upon 
  

   the 
  underside 
  of 
  the 
  lower 
  leaves, 
  over 
  which 
  they 
  had 
  spun 
  a 
  small 
  

   amount 
  of 
  web. 
  No 
  distinct 
  migration 
  was 
  noted 
  at 
  this 
  time, 
  but 
  

   as 
  the 
  mites 
  increased 
  in 
  numbers 
  the 
  infested 
  leaves 
  were 
  seriously 
  

   injured 
  and 
  partially 
  dried. 
  In 
  this 
  condition 
  they 
  furnished 
  very 
  

   little 
  food 
  and 
  forced 
  the 
  mites 
  to 
  migrate 
  to 
  fresh 
  foliage, 
  leaving 
  

   behind 
  them 
  from 
  100 
  to 
  450 
  eggs 
  and 
  at 
  least 
  one-tenth 
  as 
  many 
  larvas. 
  

   Gradual 
  upward 
  migrations 
  continued 
  until 
  the 
  last 
  of 
  July, 
  at 
  which 
  

   time 
  the 
  plants 
  were 
  entirely 
  infested. 
  

  

  During 
  the 
  month 
  of 
  August 
  a 
  new 
  condition 
  was 
  observed. 
  The 
  

   morning-glory 
  in 
  the 
  hopyards 
  had 
  become 
  seriously 
  injured 
  by 
  

   miles. 
  A 
  migration 
  caused 
  by 
  the 
  sudden 
  (decrease 
  in 
  the 
  food 
  supply 
  

   was 
  begun 
  and 
  soon 
  became 
  very 
  extensive. 
  Myriads 
  of 
  mites 
  were 
  

   seen 
  crawling 
  from 
  the 
  dying 
  morning-glory, 
  over 
  the 
  clods, 
  up 
  the 
  

   vines 
  and 
  trellis 
  poles, 
  and 
  covering 
  everything 
  with 
  a 
  fine 
  web. 
  

  

  A 
  similar 
  condition 
  was 
  noticed 
  on 
  a 
  few 
  hopvines 
  that 
  had 
  Fallen 
  

   from 
  the 
  wire. 
  The 
  leaves 
  that 
  were 
  farthest 
  from 
  the 
  ground 
  were 
  

   74966°— 
  Bull. 
  117—13- 
  3 
  

  

  