THE FALL ARMY WORM AND THE VARIE- 
GATED CUTWORM. 
INTRODUCTION. 
The history of economic entomology shows that nearly every year 
there are outbreaks of one or more species of caterpillars, which, from 
their habit of migrating" in great numbers, have come to be famil- 
iarly termed ' c army worms. " - The normal habit of these caterpillars 
is the same as that of others of their kind, which includes cutworms. 
In ordinary seasons they feed chiefly on the grasses or weeds on which 
the parent moth has laid her eggs, or they may be present and feed- 
ing in our gardens, fields, and pasture land in small numbers, doing so 
little damage that their presence is not noticed. No class of insects 
however, are more subject to fluctuation in numbers in different sea- 
sons. When, therefore, for any reason their numbers become unduly 
increased, they first devour every form of vegetation that is palatable 
to them growing in their immediate neighborhood, and when this food 
has become exhausted they march in armies in search of other means 
of sustenance. 
In recent years several army-worm outbreaks have been observed 
and recorded. The year 1896 was marked by an unprecedented out- 
break of the true army worm; the year 1899 by a similar incursion of 
the fall army worm, and in 1900 the variegated cutworm .became the 
most destructive of these species. 
In 1899 the fall army worm ravaged a considerable portion of the 
United States east of the Rocky Mountain region. This species feeds 
by preference on grasses and related plants, and so frequently assumes 
the migratory habit that it has come to be classified as one of our prin- 
cipal army Worms, second only to the army worm proper (Leucania 
unipuncta Haw). The unusual and widespread abundance of the fall 
army worm during the season mentioned, and in many States w r here it 
had not previously been known as the cause of serious trouble, was the 
more remarkable since not a single specimen of this insect was received 
the previous year from any of our many correspondents, although a 
few individuals were noticed by the writer and others in the vicinity 
of the District of Columbia, and because so few outbreaks have been 
reported since that year, one of these also in the District of Columbia. 
Although the species is to be found ordinarily everywhere in the 
