18 THE ARMY-WORM. 
thing theirown way. By watching them after dark we 
may see numerous black beetles chasing and grabbing them 
with their large and pointed mandibles; and after sucking 
them dry, dropping them for other victims. 
A large number of birds are attracted to invaded fields 
and, though the worms usually hide during the day, they kill 
large numbers of them. Our best friends in exterminating 
these noxious worms are, however, such nocturnal mammals 
as shrews, skunks, weasels, and even gophers, which devour 
large numbers. Considering all these facts we realize that 
notwithstanding the vast number of worms in such armies 
but comparatively few of them reach the adult stage, and it 
is the experience of most observing people that one army- 
worm season is not usually followed by another one. 
The life-history of army-worms is essentially that of the 
common cut-worms. In reality they 
are nothing but cut-worms crowded 
together in large numbers by favor- 
able conditions, and doomed, on that 
account, to suffer. Army-worms can 
be found in every season, but in nor- 
mal years they do not act as army- 
worms, but lead the life of a common 
Nid doe eeu ee cut-worm. The adult insects, one of 
SB OA aes which is illustrated in fig. 11 (plate 
II), fly m Minnesota from the middle of June till 
late in September, in fact some have been captured 
as early as May 19th and as late as Sept. 29th. In some 
cases large numbers are attracted to fermenting liquids, 
while at other times only solitary specimens can be seen. It 
is usually claimed that there are two annual broods of these 
insects in Minnesota, but we have been unable to verify this 
statement, and only know from experience that we can ex- 
pect army-worms in a summer following a wet spring. 
Why this is sois not known. The metamorphosis of the 
army-worm can be given in a few words: the eggs, which 
are deposited early in the night, are thrust by means of a 
horny ovipositor between the folded sides of a blade of grass; 
usually fifteen or twenty eggs are glued together. Each fe- 

