HOW SWARMS ARE FORMED. 
89 
whirling about in the air, like bees swarming, but away beyond myriads can be seen 
moving across the sun toward the southwest, looking like snowflakes. If there is 
a change in the atmosphere, such as the approach of a thunder-storm or gale of wind 
they come down precipitately, seeming to fold their wings and descend by the force 
of gravity, thousands being killed by the fall, if it be on stone or other hard sub- 
stance. If not interrupted by such causes, they descend during the afternoon. 
It is proper to add that this applies to the east base and within the 
mountain region, where the atmosphere near the surface of the ground 
is protected by the mountain wall, while an upper current may be mov- 
ing eastward or southeast — a condition not found on the plains. The 
commissioners have also had the pleasure of witnessing this habit of the 
locust of circling upward in the mountain region, behind some inject- 
ing ridge, and in the narrow cations, apparently for the purpose of ascer- 
taining the condition or direction of the upper currents, and suddenly 
dropping, if from any cause it proved unfavorable. This habit of drop- 
ping suddenly and with folded wings is very marked, and when first 
observed by the writer attracted his attention more than any single 
point connected with their movements. Nor does this habit appear to 
be confined to our native species, but is true to a certain extent both of 
P. migratorius and A. peregrinum. 
Lucretiis says that when they find themselves in a condition not to 
sustain a long journey they at first drop and then fall precipitately to 
the ground. 
Eichard Jobson, 187 describing the fall of locusts in a storm, says : 
As we returned homeward there came so many of them behind us that they seemed 
to be blows of stones and staves. 
Captain Frankland, 188 while at Smyrna in the latter part of July, ob- 
served a large swarm ; in speaking of them he remarks that — 
They passed over the city, falling upon the roofs of the houses, where they lay two 
or three inches deep, and tumbling into the sea in such quantities that they could be 
traced in continuous streams for many leagues from the land. 
Although the method of falling is not described, it is evident from 
what he says that it was precipitately. 
The formation and movements of sivarms. — The disposition to mass 
together begins at an early stage in the life of these insects; in fact, as 
stated in our former report, it is shown in C. spretus from the first, 
though, as Koppen remarks in reference to P. migratorius, no decided 
association for the purpose of moving forward appears until the second 
or third stage. But from the third stage onward until they acquire 
wings this disposition to move forward in armies is shown quite dis- 
tinctly. The fact that they combine together and move in immense 
swarms in the winged state, often in such numbers as to darken the sun 
for hours, is too well known to require any further proof. This habit 
appears to have given origin at a very early date to the belief that they 
are led by kings — a belief which, judging from some of our locust cor- 
"» Loc. cit. '""Travela to awl from Constantinople in 1827-28, I, 264. 
