12 
Bulletin ioi. 
which is favorable to the laying of eggs. In the latter case the 
new grounds furnish a resting place, where the insects may be 
found for a greater or less length of time. If they are successful 
here, they may invade new territory, or, on the other hand, they 
may be overcome by enemies and adverse circumstances and dis¬ 
appear. 
A trait of this species, as well as some others of the same 
genus, is to travel in bands of greater or less magnitude. When 
the eggs hatch well, these bands assume almost incredible propor¬ 
tions. Prof. Bruner states: “As a rule, they collect into lines 
varying from a few to hundreds of yards in width, and from a 
few hundred feet to a mile or more in length.” These armies mi¬ 
grate in different directions from the breeding grounds, as if by 
common consent. The sight of an army on the march is one of 
the most wonderful in the insect world. The heads are all in one 
direction; the troops move along in a steady and orderly fashion 
without confusion or much noise, the members traveling on “all 
sixes.” The sight of a band in its progress reminds one of the 
movement of a full stream. There is the same steady motion and 
ceaseless flow. So far as we observed, it was only when alarmed 
that the insects began to jump, and the sharp, warning notes of the 
males set the surrounding members in commotion and precipitous 
flight. Most observers state that the line of direction is not changed; 
that the insects will cross streams and ditches, climb cliffs and go 
over houses and fences, rather than change their purpose. This can 
be true only in part. It is well known that many separate armies 
have followed rather tortuous courses during their periods of wan¬ 
dering. They are commonly diverted from entering cultivated 
fields by herding. Many original armies appear to have been split 
into different bands and thereafter to have pursued widely diverg¬ 
ing lines. All of the things mentioned above are true, but their 
persistence in a distinct direction in any particular case is prob¬ 
ably due to the pressure of their companions on all sides, which 
makes a change impossible. 
We lack definite data regarding the exact period in the insect's 
life when the migrations begin, but observers say that when they 
are first herded they are of all sizes, and some report that at the 
first appearance the insects are very small. 
The length of time employed in travel depends largely upon 
the time of maturing of the insect. During the summer of 1904, 
the forward march was not continued beyond the middle of July. 
The visitation, however, was said to be earlier than usual, owing 
to the nature of the spring, which caused the eggs to hatch at an 
early date. 
When the egg-laying period is reached, the insects retire to 
the dry hills, where they spend their time providing for their off- 
