﻿278 
  REPORT 
  UNITED 
  STATES 
  ENTOMOLOGICAL 
  COMMISSION. 
  

  

  Greasewood 
  will 
  not 
  burn 
  freely, 
  owing 
  to 
  its 
  being 
  a 
  sparse 
  growth 
  j 
  

   and 
  as 
  the 
  Bocky 
  Mountain 
  locust 
  does 
  not 
  frequent 
  the 
  cold, 
  clayey 
  

   soils 
  which 
  produce 
  this 
  plant, 
  such 
  regions 
  are 
  of 
  no 
  importance 
  in 
  

   this 
  connection. 
  

  

  Timbered 
  lands 
  are 
  not 
  considered 
  in 
  this 
  connection, 
  as 
  these 
  insects 
  

   do 
  not 
  breed 
  in 
  a 
  timbered 
  country. 
  

  

  The 
  great 
  area 
  of 
  the 
  plains, 
  stretching 
  eastward 
  in 
  a 
  long 
  inclined 
  

   plain 
  from 
  the 
  base 
  of 
  the 
  Bocky 
  Mountains, 
  is 
  therefore 
  mainly 
  cov- 
  

   ered 
  with 
  grasses, 
  which 
  are 
  mostly 
  low, 
  seldom 
  forming 
  a 
  sward 
  but 
  

   growing 
  in 
  bunches 
  or 
  tufts. 
  

  

  In 
  the 
  British 
  Possessions 
  the 
  area 
  of 
  the 
  plains, 
  or 
  level, 
  untimbered 
  

   regions, 
  is 
  divided 
  by 
  Mr. 
  Dawson, 
  the 
  Canadian 
  geologist, 
  into 
  three 
  

   "prairie 
  levels 
  " 
  or 
  steppes 
  — 
  steppes 
  with 
  very 
  slight 
  rise 
  and 
  long 
  trend. 
  

   The 
  first 
  of 
  these 
  includes 
  the 
  region 
  of 
  the 
  Lakes 
  Winnipeg, 
  Manitoba, 
  

   Winnepegosis, 
  &c. 
  It 
  is 
  heavily 
  timbered, 
  except 
  near 
  its 
  western 
  

   border. 
  Its 
  mean 
  elevation 
  is 
  not 
  far 
  from 
  1,000 
  feet. 
  Bising 
  from 
  

   this, 
  westward, 
  in 
  bluffs 
  two 
  or 
  three 
  hundred 
  feet 
  in 
  height, 
  is 
  the 
  

   eastern 
  escarpment 
  of 
  the 
  second 
  prairie 
  level, 
  of 
  which 
  the 
  Coteau 
  des 
  

   Prairies, 
  in 
  Minnesota, 
  is 
  the 
  southern 
  extension. 
  This 
  is 
  tolerably 
  fer- 
  

   tile, 
  well 
  grassed, 
  with 
  timber 
  only 
  in 
  the 
  bottom 
  lands 
  of 
  the 
  streams 
  and 
  

   on 
  knolls 
  and 
  the 
  faces 
  of 
  bluffs. 
  Its 
  elevation 
  is 
  from 
  1,200 
  to 
  1 
  ,500 
  

   feet 
  above 
  the 
  sea, 
  gradually 
  rising 
  westward. 
  The 
  third 
  prairie 
  level 
  

   is 
  what 
  corresponds, 
  in 
  the 
  United 
  States, 
  to 
  the 
  plains 
  proper 
  and 
  the 
  

   Coteau 
  du 
  Missouri. 
  It 
  rises 
  from 
  the 
  last 
  in 
  ill-defined 
  bluffs, 
  of 
  

   small 
  height. 
  Prom 
  the 
  edge 
  it 
  gradually 
  increases 
  in 
  height 
  westward 
  

   until, 
  at 
  the 
  base 
  of 
  the 
  Bocky 
  Mountains, 
  it 
  is 
  4,000 
  to 
  5,000 
  feet 
  above 
  

   the 
  sea. 
  On 
  this 
  level 
  the 
  grass 
  is 
  shorter, 
  less 
  luxuriant, 
  and 
  in 
  some 
  

   places, 
  especially 
  near 
  the 
  boundary, 
  shows 
  the 
  effect 
  of 
  a 
  climate 
  de- 
  

   cidedly 
  arid 
  by 
  the 
  presence 
  of 
  sage 
  and 
  cacti. 
  Timber 
  is 
  distributed 
  

   very 
  much 
  as 
  on 
  the 
  second 
  level, 
  but 
  is 
  decidedly 
  more 
  scarce. 
  

  

  As 
  we 
  proceed 
  northward 
  over 
  the 
  two 
  upper 
  prairie 
  levels 
  in 
  the 
  

   country 
  between 
  the 
  forks 
  of 
  the 
  Saskatchewan, 
  the 
  climate 
  becomes 
  

   moister 
  with 
  the 
  increasing 
  cold, 
  and 
  the 
  vegetation 
  approaches 
  more 
  

   and 
  more 
  the 
  nature 
  of 
  that 
  on 
  the 
  true 
  prairies 
  of 
  the 
  Mississippi 
  Val- 
  

   ley 
  ; 
  and 
  north 
  of 
  an 
  undulating 
  line 
  which 
  follows 
  approximately 
  the 
  

   course 
  of 
  the 
  52d 
  parallel, 
  patches 
  and 
  belts 
  of 
  timber 
  begin 
  to 
  diversify 
  

   the 
  surface, 
  alternating 
  with 
  the 
  rich 
  grasses. 
  The 
  change 
  from 
  prairie 
  

   to 
  forest 
  goes 
  on 
  gradually 
  over 
  a 
  belt 
  50 
  to 
  75 
  miles 
  in 
  breadth, 
  and 
  

   the 
  North 
  Saskatchewan 
  is 
  reached 
  before 
  the 
  forest 
  has 
  asserted 
  sole 
  

   proprietorship. 
  South 
  of 
  Belly 
  Biver, 
  more 
  arid 
  conditions 
  manifest 
  

   themselves. 
  At 
  the 
  base 
  of 
  the 
  Bocky 
  Mountains, 
  and 
  indeed 
  for 
  a 
  

   hundred 
  miles 
  eastward, 
  and 
  about 
  the 
  Judith 
  and 
  Big 
  Horn 
  Ranges, 
  

   the 
  influence 
  of 
  the 
  mountains 
  in 
  inducing 
  a 
  moister 
  climate 
  is 
  plain 
  j 
  

   the 
  grass 
  is 
  tolerably 
  luxuriant 
  everywhere, 
  and 
  especially 
  so 
  at 
  the 
  

   base 
  of 
  these 
  ranges, 
  gradually 
  shading 
  oft' 
  in 
  luxuriance 
  with 
  the 
  dis- 
  

   tance 
  from 
  them. 
  

  

  