﻿XVI 
  PREFACE. 
  

  

  Bocky 
  Mountain 
  locust 
  is 
  shown 
  to 
  be 
  migratory 
  within 
  the 
  limits 
  of 
  its 
  

   permanent 
  range, 
  and 
  the 
  source 
  of 
  the 
  invading 
  swarms 
  of 
  our 
  own 
  

   species, 
  and 
  the 
  differences, 
  both 
  in 
  direction 
  and 
  character, 
  of 
  return 
  

   swarms, 
  are 
  set 
  forth. 
  These 
  return 
  swarms 
  do 
  little 
  or 
  no 
  injury, 
  and 
  

   the 
  migratory 
  locusts 
  of 
  other 
  parts 
  of 
  the 
  world 
  appear 
  to 
  manifest 
  the 
  

   same 
  disposition 
  to 
  return 
  to 
  the 
  country 
  whence 
  their 
  immediate 
  par- 
  

   ents 
  came, 
  as 
  in 
  the 
  case 
  of 
  our 
  own 
  species. 
  The 
  distance 
  to 
  which 
  

   swarms 
  may 
  migrate 
  in 
  the 
  course 
  of 
  a 
  season, 
  the 
  position 
  of 
  the 
  insects 
  

   in 
  flight, 
  the 
  influence 
  of 
  the 
  winds 
  on 
  the 
  flights, 
  the 
  height 
  of 
  flight, 
  

   and 
  other 
  questions 
  in 
  reference 
  to 
  the 
  movements 
  of 
  winged 
  locusts, 
  

   whether 
  in 
  this 
  country 
  or 
  abroad, 
  are 
  discussed, 
  as 
  also 
  the 
  causes, 
  

   both 
  remote 
  and 
  immediate, 
  of 
  migration. 
  

  

  Chapter 
  V, 
  also 
  prepared 
  by 
  Mr. 
  Thomas, 
  deals 
  with 
  the 
  influence 
  of 
  

   meteorological 
  conditions 
  on 
  the 
  development 
  and 
  migrations 
  of 
  locusts, 
  

   as 
  also 
  on 
  the 
  development 
  of 
  the 
  eggs. 
  

  

  Chapter 
  VI, 
  prepared 
  by 
  Mr. 
  Packard, 
  deals 
  with 
  the 
  subject 
  of 
  the 
  

   southern 
  distribution 
  of 
  Caloptenus 
  spretus, 
  and 
  gives 
  the 
  history 
  of 
  

   locust 
  invasions 
  in 
  JTew 
  Mexico. 
  

  

  In 
  Chapter 
  VII 
  Mr. 
  Packard 
  gives 
  a 
  summary 
  of 
  locust 
  flights 
  during 
  

   the 
  years 
  1877, 
  1878, 
  and 
  1879. 
  

  

  In 
  Chapter 
  VIII, 
  also 
  by 
  Mr. 
  Packard, 
  an 
  account 
  is 
  given 
  of 
  the 
  

   western 
  cricket, 
  an 
  insect 
  that 
  proves 
  extremely 
  destructive 
  in 
  the 
  mount- 
  

   ain 
  regions 
  of 
  the 
  West, 
  and 
  about 
  which 
  the 
  Commission 
  has 
  had 
  

   many 
  inquiries. 
  Its 
  ravages, 
  enemies, 
  and 
  parasites, 
  breeding 
  habits, 
  

   and 
  geographical 
  distribution, 
  are 
  set 
  forth, 
  so 
  that 
  they 
  can 
  be 
  com- 
  

   pared 
  with 
  those 
  of 
  the 
  Rocky 
  Mountain 
  locust. 
  Remedies 
  are 
  sug- 
  

   gested, 
  and 
  the 
  chapter 
  concludes 
  with 
  a 
  study 
  of 
  the 
  external 
  and 
  in- 
  

   ternal 
  anatomy 
  of 
  this 
  large 
  cricket. 
  

  

  In 
  chapter 
  IX 
  Mr. 
  Packard 
  treats 
  of 
  the 
  air 
  sacs 
  of 
  locusts, 
  with 
  a 
  

   view 
  of 
  indicating 
  their 
  origin, 
  and 
  of 
  showing 
  their 
  use 
  in 
  flight. 
  

  

  Chapter 
  X, 
  by 
  Mr. 
  Charles 
  S. 
  Minot, 
  is 
  the 
  result 
  of 
  careful 
  histological 
  

   study 
  of 
  the 
  locust, 
  and 
  of 
  the 
  cricket 
  before 
  mentioned. 
  

  

  Chapter 
  XI, 
  by 
  Mr. 
  Packard, 
  on 
  the 
  brain 
  of 
  the 
  locust, 
  is 
  the 
  result 
  

   of 
  similar 
  study 
  of 
  the 
  nervous 
  system 
  and 
  the 
  brain 
  of 
  the 
  locust. 
  

  

  Chapter 
  XII, 
  by 
  Messrs. 
  Riley 
  and 
  Thomas, 
  treats 
  of 
  the 
  destructive 
  

   locust 
  of 
  California, 
  and 
  shows, 
  that 
  while 
  the 
  species 
  is 
  distinct 
  from 
  

   the 
  Rocky 
  Mountain 
  locust, 
  yet 
  in 
  size, 
  habits, 
  destructiveness, 
  and 
  even 
  

   in 
  natural 
  enemies, 
  the 
  two 
  strongly 
  resemble 
  each 
  other. 
  

  

  Chapter 
  XIII, 
  by 
  Mr. 
  Riley, 
  gives 
  further 
  facts 
  about 
  the 
  natural 
  ene- 
  

   mies 
  of 
  locusts, 
  and 
  deals 
  more 
  particularly 
  with 
  the 
  locust 
  egg-feed- 
  

   ing 
  habit 
  of 
  the 
  larvae 
  or 
  the 
  Bee-flies 
  (Bombyliidw), 
  a 
  large 
  family 
  of 
  

   two-winged 
  flies, 
  quite 
  abundant 
  in 
  the 
  West, 
  and 
  the 
  larval 
  habits 
  of 
  

   which 
  were 
  not 
  previously 
  known. 
  

  

  In 
  the 
  closing 
  chapter, 
  XIV, 
  Mr. 
  Riley 
  has 
  endeavored 
  to 
  present 
  

   more 
  accurate 
  data 
  than 
  had 
  hitherto 
  been 
  given 
  concerning 
  the 
  perma- 
  

   nent 
  breeding 
  grounds, 
  with 
  a 
  view 
  of 
  ascertaining 
  what 
  courses 
  the 
  gov- 
  

  

  

  