IV 
TABLE OF CONTENTS 
Facts concerning and laws governing the migrations of locusts in- 
all countries— Continued. 
not governed by laws of periodicity, 55, 5C— Permanent breeding grounds of 
locusts, 56, 57 — Tbeir geographical distribution, 58 — Caloptenua apretus not 
in Mexico, 58 — Migratory locusts in Yucatan and the West Indies, 58, 59 — 
in Nicaragua, 59 — Geographical limits of Caloptenua apretua, 59— of Pachy- 
tylus migratorius, 59, CO— Difficulty of determining species, CO, Gl — Defini- 
tion of permanent home of migratory locusts, 62 — Range of I'achytylus 
migratorius, 62, G3 — of Acridium peregrinum, G3, C4 — Comparison with the 
laws of geographical zoology, G5, CC — Meeting point of three sub-regions, 
67 — Each species has its permanent breeding ground, C8 — General charac- 
ter of the permanent breeding grounds, 68, 69 — Breeding ground of Calop- 
tenua italicus, G9 — of Pachytylua migratoriua, 69, 70 — of Acridium peregrinum, 
70 — of Caloplenus apretua, 70, 71. 
CHAPTER IV. 
Habits and characteristics of locusts in all countries witiiin tiieib 
areas of permanent distribution, 80 far as these relate to their 
movements 72 
Caloptenua apreiua always migratory, 72,73 — Flights of C. apretua, 73, 74 — 
Invading swarms come from northwest, 74, 75 — Other opinions eliminated, 
75,76 — Swarms in 1875 and 1876,76,77 — Direction of returning swarms of 
C. apretua, 78 — of other migratory locusts, 78, 79 — Direction of local flights, 
79-81 — Returning swarms do little injury, 81,82 — Distance to which 
swarms may migrate, 82-84 — Length of a single flight, 84, 85 — Swarms 
able to cross large bodies of water, 85, 86 — Swarms carried far by winds, 
86, 87— The mode of flight, 87— Position of the locust while flying, 87, 88— 
Locusts flying with the wind, 88, 89 — Method of falling of swarms, 89 — 
Formation of swarms, 89-91 — Movements of swarms of C. apretua, as re- 
ported by Dr. Child, 91-93— Other reports, 94 — Movements of swarms in 
other countries, 95-96 — Swarms usually alight at night, 96, 97 — The height 
at which swarms move, 98-100 — Different directions of swarms at the 
same time and place, 100 — Fall of locusts into the sea, 100-102 — Great 
flying power of locusts, 102 — General causes of migration, 103 — Excessive 
numbers, 103, 104 — Want of food, 104 — Excessive heat, 105 — Dry condi- 
tion of the atmosphere, 105, 106 — Arid condition of the mountain region, 
106, 107 — Immediate causes of migration, 107, 108. 
CHAPTER V. 
Influence of meteorological conditions on the development and 
migrations of locusts 109 
Influence of heat and dryness, 109, 110 — Packard's table of locust years, 
111, 112— Table of rainfalls for 1860 to 1866, 112— Influence of the rainfall, 
especially in 1864, 112, 113 — Average monthly temperature for 1864 and 
1866, 113-115— Rainfall of the years 1863 to 1867, 116— Temperature of the 
years 1863 to 1867, 117 — Extreme variations of monthly mean temperature 
from 1863 to 1867, 118, 119 — Monthly and annual mean temperature from 
1872 to 1876, 119-121— Monthly and annual rainfall from 1872 to 1878, 
122-124 — Extreme fluctuations between monthly mean temperature, 
125, 126 — Greatest variations between monthly mean temperatures, 126 — 
Variations of temperature between months of consecutive years, 127, 128 — 
Daily temperature at Fort Sully from 1872 to 1875, 129-134 — Relation of 
temperature to the development of the eggs, 135, 136 — Professor Riley's 
experiments, 137 — Professor Abbe's theory on the subject discussed, 
137-140 — Table showing temperature and direction and velocity of wind 
at Western stations, 141-154 — Relation of temperature and winds to locust 
flights, 155. 
