﻿72 
  EEPORT 
  UNITED 
  STATES 
  ENTOMOLOGICAL 
  COMMISSION. 
  

  

  ing 
  in 
  the 
  summer 
  as 
  low 
  as 
  20 
  and 
  seldom 
  reaching 
  60, 
  as 
  will 
  be 
  

   seen 
  by 
  reference 
  to 
  the 
  meteorological 
  data 
  furnished 
  by 
  Professor 
  Abbe 
  

   and 
  found 
  in 
  our 
  former 
  report, 
  and 
  to 
  that 
  found 
  in 
  a 
  succeeding 
  chapter. 
  

  

  In 
  studying 
  carefully 
  the 
  climatic 
  conditions 
  of 
  the 
  various 
  locust 
  

   areas, 
  we 
  notice 
  this 
  difference 
  between 
  those 
  in 
  the 
  Eastern 
  Continent 
  

   north 
  of 
  the 
  equator 
  and 
  that 
  of 
  our 
  species. 
  The 
  former 
  have 
  their 
  

   greatest 
  extension 
  east 
  and 
  west, 
  and 
  in 
  the 
  case 
  of 
  P. 
  migratorius 
  

   and 
  G. 
  italicus 
  in 
  the 
  direction 
  of 
  the 
  migrations, 
  while 
  that 
  of 
  C. 
  spretus 
  

   extends 
  north 
  and 
  south, 
  or 
  at 
  least 
  presents 
  its 
  best-defined 
  side 
  toward 
  

   the 
  east 
  and 
  at 
  an 
  angle 
  to 
  the 
  usual 
  course 
  of 
  migrations. 
  The 
  area 
  of 
  

   A. 
  peregrinum 
  has 
  its 
  greatest 
  extension 
  east 
  and 
  west, 
  the 
  western 
  half 
  

   at 
  right 
  angles 
  to 
  the 
  usual 
  course 
  of 
  migrations. 
  In 
  speaking 
  of 
  the 
  

   character 
  of 
  the 
  area 
  occupied 
  by 
  this 
  last-named 
  species, 
  we 
  omitted 
  to 
  

   mention 
  the 
  elevated 
  portion 
  along 
  the 
  southern 
  limits. 
  

  

  As 
  P. 
  migratorius 
  has 
  its 
  chief, 
  or, 
  as 
  we 
  might 
  say, 
  central 
  area 
  about 
  

   the 
  Caucasus 
  range, 
  and 
  a 
  mountain 
  home 
  or 
  back-ground 
  appears 
  

   essential 
  to 
  the 
  migratory 
  Calopteni, 
  it 
  is 
  possible 
  that 
  this 
  character- 
  

   istic 
  is 
  more 
  important 
  to 
  the 
  development 
  of 
  locusts 
  than 
  has 
  gener- 
  

   ally 
  been 
  supposed. 
  

  

  CHAPTER 
  IV. 
  

  

  HABITS 
  OE 
  CHAEACTEEISTICS 
  OF 
  LOCUSTS 
  IK 
  ALL 
  COUN- 
  

   TRIES 
  WITHIN 
  THEIE 
  AEEAS 
  OF 
  PEEMANENT 
  DISTEIBU- 
  

   TION, 
  SO 
  FAE 
  AS 
  THESE 
  EELATE 
  TO 
  THEIE 
  MOVEMENTS. 
  

  

  The 
  chief 
  items 
  of 
  importance 
  under 
  this 
  topic 
  are 
  the 
  following 
  : 
  First. 
  

   Are 
  they 
  normally 
  sedentary 
  in 
  the 
  permanent 
  area, 
  developing 
  under 
  

   favorable 
  climatic 
  conditions 
  in 
  immense 
  numbers 
  and 
  becoming 
  migra- 
  

   tory 
  from 
  some 
  cause 
  connected 
  with 
  this 
  development 
  j 
  or 
  are 
  they 
  es- 
  

   sentially 
  migratory 
  in 
  character? 
  Second. 
  Do 
  they 
  breed 
  annually 
  

   throughout 
  this 
  entire 
  area, 
  or 
  only 
  in 
  certain 
  portions, 
  changing 
  from 
  

   time 
  to 
  time 
  from 
  one 
  locality 
  to 
  another 
  1 
  ? 
  

  

  In 
  our 
  First 
  Eeport, 
  in 
  the 
  chapter 
  on 
  u 
  Permanent 
  Breeding 
  Grounds," 
  

   we 
  expressed 
  briefly 
  our 
  opinion 
  on 
  these 
  points 
  in 
  reference 
  to 
  the 
  Eocky 
  

   Mountain 
  locust, 
  as 
  follows 
  : 
  

  

  It 
  is 
  not 
  to 
  be 
  inferred 
  that 
  the 
  locust 
  breeds 
  continuously 
  over 
  the 
  whole 
  extent 
  

   of 
  this 
  area 
  each 
  year, 
  as 
  it 
  is 
  to 
  be 
  understood 
  that 
  the 
  locust 
  within 
  its 
  native, 
  per- 
  

   manent 
  habitat 
  is 
  essentially 
  migratory 
  in 
  its 
  habits, 
  and 
  while 
  for 
  a 
  series 
  of 
  years 
  it 
  

   may 
  deposit 
  its 
  eggs 
  in 
  a 
  given 
  river 
  valley, 
  in 
  some 
  park, 
  or 
  in 
  some 
  favorable 
  area 
  

   on 
  the 
  plains 
  lying 
  about 
  the 
  mountain, 
  in 
  a 
  certain 
  year 
  or 
  for 
  several 
  years 
  in 
  suc- 
  

   cession 
  it 
  may 
  desert 
  its 
  customary 
  breeding 
  grounds 
  for 
  adjoining 
  regions 
  or 
  cross 
  a 
  

   low 
  range 
  of 
  mountains 
  and 
  breed 
  in 
  a 
  more 
  distant 
  valley. 
  Moreover, 
  the 
  true 
  breed- 
  

   ing 
  grounds 
  in 
  this 
  area 
  are, 
  for 
  the 
  most 
  part, 
  confined 
  to 
  the 
  river 
  bottoms 
  or 
  suuuy 
  

   slopes 
  of 
  uplands, 
  or 
  to 
  the 
  subalpine 
  grassy 
  areas 
  among 
  the 
  mountains, 
  rather 
  than 
  

   continuously 
  over 
  the 
  more 
  elevated, 
  dry 
  bleak 
  plains. 
  

  

  