11 
of congregating and migrating in great numbers. The common army 
worm and the wheat-head army worm are common forms. A few 
other species which occur in North America should be added. Among 
these are the erratic army worm (JVoctua fennica Tausch.), which is 
known as the black cutworm in ordinary seasons; the cotton army 
worm, known commonly as the cotton worm (Aletia argillacea Hbn.), 
and the forest tent caterpillar so-called (Clisiocampa disstria Hbn.). 
All of the species mentioned belong to the Noctuidae, with the excep- 
tion of the last, which is a Bombycid. A name that has recently been 
proposed for this last is the forest armjr worm. 
All of these species differ considerably in habit, and in order to pre- 
scribe the proper remedies it is necessary to have a thorough under- 
standing of the insects' habits; in fact, frequent inquiry is made by 
those interested in the subject as to the full life histories of these 
species. 
While it is matter of entomological history that a repetition of gen- 
eral outbreaks by army worms, or species referred to as such, seldom 
follow in successive years, still it is wisdom to guard against such a 
contingency, and, at the first intimation of the presence of the insects 
in numbers, to institute radical measures for their suppression. To 
those skilled in entomolog}^ there is little difficulty in recognizing the 
moths as well as the larvae of these species, and this it is confidently 
believed will be facilitated by the illustrations and descriptions which 
are here given; but it is advised that those who feel unable to determine 
these insects beyond peradventure promptly send the material found 
to some one competent to make correct identifications, so that appro- 
priate measures of control may be adopted without delay. 
In the case of the irruptions of the fall army worm in 1899, and its 
scarcity the following year, there are reasons, which have been briefly 
mentioned and which will presently be set forth in greater detail, that 
we can assign for depletion in numbers following injurious attack. 
But the life economy of the variegated cutworm is so different that no 
reason for the lessening of the numbers of this insect during the pres- 
ent year (1901) can be conjectured other than that parasites, and 
perhaps some other natural enemies which were observed at work late 
in the season of 1900, would have, at least locally, a beneficial effect. 
It is possible, however, that diseases, either fungous or bacterial, 
might have been present in many of the regions over which the insect 
ranged in destructive numbers last year without their coming under 
the notice of anyone capable of determining them, and it is perhaps 
possible also that the condition of the weather in the Pacific States, in 
Kansas, and in some other States where this cutworm was especially 
destructive might have operated against overmultiplication. 
These are points that remain to be studied in the life history of both 
the fall army worm and the variegated cutworm. 
