186 
POPULAR SCIENCE REVIEW. 
in more or less abundance, and hence it makes its injurious raids upon the 
more highly cultivated districts lying around it. In a considerable stretch 
of country lying east of these permanent abodes of the locust, the insect is 
described as subpermanent, that is to say, its invasions are there very fre- 
quent ; and further, it is in the habit of breeding there for several consecu- 
tive years, after which it again disappears for a time. Over a much larger 
extent of country, reaching southwards to the coast in Texas, and stretching 
westwards through Colorado over a considerable space west of the Moun- 
tains, the locust is said to be temporary, visiting those regions only periodi- 
cally, and generally disappearing within the year. The migrations of these 
insects take place in two directions ; that is to say, while the invaders make 
their way in all directions from the permanent breeding grounds, the young 
locusts hatched out in the temporary regions migrate in the opposite direc- 
tion, or back towards the permanent abode of the species : and the Commis- 
sioners state that it is well established that there may be, at the same time, 
two contrary currents over considerable areas. At the same time, it is re- 
marked that many of the returning insects are so infested with parasites, 
and otherwise diseased, that they perish during their homeward journey. 
The habits and natural history of the species are fully described by the 
authors, who also indicate the characters by which it may be distinguished, 
from nearly allied but distinct species also inhabiting the North American con- 
tinent. They further describe minutely the anatomy and embryology of the 
locust, and explain its transformations, and, in fact, furnish the reader with 
all the information necessary to enable him to form an intelligent conception 
of the nature of this scourge of the Western farmer. A more encouraging 
chapter is that which treats of the insect-enemies of the locust, which fortu- 
nately appear to be pretty numerous and active in their operations — to the 
entomologist this will be one of the most interesting portions of the work. 
A great many birds also aid materially in checking the increase of the pest. 
Three chapters are devoted to the consideration of the available modes of des- 
troying the locusts by artificial means, some of which are ingenious enough, 
but need not be referred to here. A chapter on the effects produced on the 
fauna and flora of different localities in consequence of devastation by locusts 
is very interesting and instructive. The authors notice the occurrence of locusts 
in other localities, especially in countries bordering upon mountain ranges ; 
but as a set-off against the mischief done by the insects, they indicate that they 
are available “ as food for various animals, including man, as fish-bait, or as 
manure,” and further that “ the chemical analysis given of the dead locusts 
is quite interesting. The insects furnish a new oil, which we have christened 
Caloptine, and a very large percentage of formic acid.” Of their properties 
as food Mr. Riley speaks from experience in very favourable terms. A great 
body of evidence bearing on the subject of the report is given in a series of 
appendices. The volume is illustrated with several maps and numerous wood 
engravings, and with five very nicely executed plates, three of them showing 
the distinctive characters of the three North American Calopteni referred to 
in the text, the fourth representing the hypermetamorphoses of the coleop- 
terous genera Epicauta and Ilornia, distinguished enemies of the locust, and 
the fifth illustrating certain points in the histology of the latter. 
