20 
The young locusts display gregarious instincts from the start, and 
congregate in immense numbers in warm and sunny places. They thus 
often blacken the sides of houses or the 
sides of hills. They remain thus huddled 
together during cold, damp weather. 
When not traveling, and when food is 
abundant, or during bad, rainy weather, 
tbey are fond of congregating on fences, 
buildings, trees, or anything removed 
from the moist ground. They also pre- 
Fig. 2.-Calop1enus sprelus: a a, ne^ly fer to ge t j nto such pos iti nS to Undergo 
hatched larvas; b, full-giowu larva; c, ° 
pupa, natural size (after Riley). their different molts. In fields they 
collect at night or during cold, damp 
weather, under any rubbish that may be at hand, and may be enticed 
under straw, hay, etc., scattered on the ground. Old prairie-grass affords 
good shelter, and where a wheat field is surrounded with unburned prai- 
rie they will gather for shelter along the borders of this last. 
It is more particularly while they are yet small, or in the first, second, 
and third stages, that the young locusts hide at night, and, during un- 
favorable weather, at day also. In windy weather they are fond of 
gathering and secreting under any shelter, or in crevices and inequali- 
ties of the soil. At such times farmers too often conclude that the 
pests have perished and vanished 5 but a few hours of pleasant, sunny 
weather will bring the insects to sight again and dispel the delusion. 
When very vigorous and numerous they gradually move across a field 
of small grain and cut it off clean to the ground as they go, appearing 
to constantly feed. But when diseased or sickly, as in 1877, they 
gather in bare and sunny spots and huddle and bask without feeding. 
The very cold, wet weather that is prejudicial to them is beneficial to 
the grain, and under such circumstances it generally grows so rank and 
rapidly that they make little impression upon it. 
It is when they are abundant and vigorous enough to bare the ground 
of vegetation, and this principally after they are half-grown, that the 
habit of migrating in large bodies is developed. In 1877 scarcely any 
disposition to migrate was shown, and this was in strong contrast with 
what occurred in 1875. In a year like this last, when they are vigorous 
and abundant, their power for injury increases with their growth. 
At first devouring the vegetation in particular fields and patches in 
the vicinity of their birthplaces, they gradually widen the area of their 
devastation, until at last, it' very numerous, they devour every green 
thing over extensive districts. Whenever they have thus devastated a 
country they are forced to feed upon one another, and perish in im- 
mense numbers from debility and starvation. Whenever timber is ac- 
cessible they collect in it, and after cleaning out the underbrush, feed 
upon the dead leaves and. bark. A few succeed in climbing uy> into the 
