78 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 
nated as " foreigners " to distinguish them from those which are bred in 
the temporary region. 
b. Returning swarms. — This term has already been explained by the 
use we have made of it in speaking of invading swarms. But there it 
is limited to those which, having been bred in the temporary region 
between the Mississippi and the Rocky Mountains, soon after becoming 
full fledged fly back toward the section from which their progenitors of 
the preceding season came. It may be used in a general sense to apply 
to all swarms returning from the temporary regions to which they or 
their progenitors may have flown to their native habitats. 
How far this habit of returning prevails on the Pacific side of the 
permanent area we are as yet unable to say, our data not being sufficient 
to determine. 
So far as we have been able to ascertain, the disposition to return to 
the home of their ancestors is not exhibited by P. migratorius ; at least 
we have been unable to find any notice of it in the voluminous locust 
literature of Europe. 
Koppen expresses some doubt as to the correctness of the opinion that it 
is a characteristic of the species to move only from the east to the west, 
and cites instances where it has -been known to move northward, espe- 
cially on the east side of the Black Sea ; but there is nothing whatever 
shown to indicate that there is a disposition of the resulting brood or of 
the invaders to return to their native habitat ; in fact, all the data we 
can find appear to contradict this. It is more than probable that if the 
least indication of this had shown itself it would have been noticed, 
whereas the European writers on locusts assert that they ahcays move 
from the east toward the west. 
The difference in this respect between the C. spretus and P. migratorius 
is somewhat remarkable, and as yet we are unable to fully explain it ; 
but of this we will speak more fully when we have noticed the meager 
data in reference to the habits of the other species in this respect. 
We have no data whatever on this point in reference to C. italicus, 
which indicates that the attention of European entomologists has not 
been called to it, and hence we presume is not so marked as in C. spretus. 
The general direction of the movements of A. peregrinvm varies in dif- 
ferent sections ; in Northern Africa, west of Egypt, the invading swarms 
are from the south, as asserted by Lallemant and Girard, come from 
the region of the Atlas range. South of this range, in Central Africa, 
the invading swarms move southward and southwest ; 173 in Egypt and 
Arabia the movements vary, but are generally more or less east and west. 
In the states of North Africa, as we might suppose, there are indica- 
tions of a return movement similar to that observed in the case of C. 
spretus. Lallemant 17 * states that the locusts that live for a long time in 
the adult state become a rosy color, and at length migrate southward 
173 Girard, in Ann. Soc. Ent. France, 4th Ser. 18C7, Bull, x-xii. 
174 See last quoted authority. 
