22 
theBig and Little Blues, tributaries of the Missouri, near Independence, 
the one about 100 feet wide at its mouth and the other not so wide, 
were crossed at numerous places by the moving armies, which would 
march down to the water's edge and commence jumping in, one upon 
another, till they would pontoon the stream, so as to effect a crossing. 
Two of these mighty armies also met, one moving east and the other 
west, on the river bluff, in the same locality, and each turning their 
course north and down the bluff, and coming to a perpendicular ledge 
of rock 25 or 30 feet high, passed over in a sheet apparently 6 or 7 
inches thick, and causing a roaring noise similar to a cataract of water. 
(Riley's Eighth Report, p. 118.) 
The experience of correspondents as to the movements of the young 
is very conflicting, as it naturally would be from what we have already 
said. One man will notice the insects moving with the wind, and con- 
clude that it is the rule for them to do so ; another, against the wind, 
and draw an opposite conclusion. 
Bate at which the Young travel, — When about half-grown they seldom 
move at a greater rate than three yards a minute, even when at their 
greatest speed over a tolerably smooth and level road, and not halting 
to feed. They walk three-fourths this distance and hop the rest. Two 
consecutive hops are seldom taken, and any individual oue may be run 
down and fatigued by obliging it to hop ten or twelve times without a 
rest. 
According to Sydow, the young of the European P. migratorius travel, 
when at their most rapid gait, a German mile in four hours. Even 
taking the shortest German mile, or nearly four English miles, we very 
much doubt the accuracy of this statement, for though the migratoria 
is a larger species than sjpretus, we can not believe that it travels nearly 
ten times as fast, and we have again and again timed our own species. 
They reach, in the temporary Region, but a few Miles east of where they 
hatch. — At the rate at which they travel, as just described, they could 
not extend many miles, even if they continued to travel in one direction 
from the time of hatching until maturity. They travel, on an average, 
not more than 6 hours per day; and their unfledged existence termi- 
nates in from 6 to 8, say 7, weeks. It is very easy to calculate from 
these facts that if they continued in one direction from the time they 
hatch until they acquire wings, they could not extend 30 miles. Iu 
reality, however, they do not travel every day ; and where food is abun- 
dant they scarcely travel at all. 
Moreover, as we have just shown, the migratory propensity is seldom 
manifested during the first or second larval stages, and it is, iu fact, 
largely dependent on conditions of health and vigor of the insects and 
on the amount of food supply. We have learned of no cases where 
the young have extended, during growth, 10 miles east of the hatching 
limit. * 
As experience abundantly proves, the insects, when they get wings 
