12 
AMERICAN AGRICULTURIST. 
[January, 
The Army Worm. 
BT PROP. CYRUS THOMAS, CARBONDALE, HJ>. 
The appearance of the Army Worm in the 
region of Southern New York, in 1880, and 
in some portions of the Northwest in 1881, 
has again called special attention to it, and 
has induced entomologists to renew their 
study of its history and habits with a view 
of determining, if possible, some points that 
have hitherto remained in doubt. It is gen¬ 
erally known to the readers of the American 
Agriculturist, that these “ worms,” one of 
which is shown in figure 1, after they have 
completed their term of life in this state, de¬ 
scend a few inches into the ground, and, 
having formed a kind of cell, are changed 
into shining chestnut-red, or mahogany-col¬ 
ored pupae, or chrysalides of the form repre¬ 
sented in figure 2. These chrysalides are 
ultimately transformed into dark fawn-col¬ 
ored or pale-brown moths, similar to figure 3. 
The life history of the species, or the cycle 
of changes it undergoes, as observed in the 
latitude of Southern Illinois, may be briefly 
stated as follows : The 
moths make their ap¬ 
pearance early in the 
spring, usually between 
the first and tenth of 
April, and soon after de¬ 
posit their eggs. These, 
which are small, white, 
and almost spherical, 
are placed in the folds 
of the leaves of grass or 
grain, the female moth 
taking particular care to 
conceal them from sight 
by pushing them down 
into the still folded por¬ 
tion of the leaf. In about 
two weeks thereafter, these are hatched into 
dull or dirty-white, 16-footed caterpillars, 
which undergo repeated moultings, gradually 
acquiring their dark, striped color. In their 
normal condition, they are true cut-worms, 
living out this stage of their existence, con¬ 
cealed under the grass, cutting it off just at 
the surface of the ground. When they be¬ 
come excessively multiplied, they assume an 
abnormal role, becoming a marching or 
“Army Worm,” moving in immense bodies 
from one field to another. As a general rule, 
they do not commence marching until they 
are about two-thirds grown. So far as I have 
observed, those leaving one field always march 
in the same direction, but not always, as sup¬ 
posed by some, with unfailing certainty 
toward another field in which there is proper 
food. I have seen them leave 
a meadow in a direct line 
toward town, the nearest 
field in that direction being Fig.2. TnE chrx- 
at least a mile off. While salis. 
it may be, and probably is, true, that the 
cause of their marching is, as a general 
rule, to seek for food, there are certainly re¬ 
peated exceptions, where they have been 
known to leave an ample supply. It is also 
true that they will march occasionally when 
not in excessive numbers. I observed an 
instance of this kind in 1875, where a little 
straggling “army” left a fine grassy yard, 
and marched over ground partly denuded, 
where they were exposed to the hot rays of 
the sun which they so much dread, a large 
number of them perishing by the way. This 
movement was certainly the result of some 
other impelling cause than the want of food. 
The habits of the “ worms” are somewhat 
similar to those of ordinary cut-worms, as 
they avoid the hot sun, coming forth to feed 
chiefly in the night, or during cloudy weather. 
They hide under clods, stones, and other rub¬ 
bish during the hot and sunny portion of the 
Fig. 3. —THE MOTH, NATURAL SIZE. 
day. During their life in the larval state, 
which lasts about a month, the “worms” 
change their skin five times; and having 
completed their growth, descend into the 
ground a few inches below the surface, where 
they transform into pupae. They spin no 
cocoon, but by movements of the body and 
excretions of a sticky fluid, usually form a 
kind of earthen cell; but occasionally they 
simply crawl into some hiding place to under¬ 
go their changes. About fifteen or twenty 
days after entering the ground they reappear 
as moths, coming out usually about dusk, and 
climbing up the grass stems where they rest 
awhile for their wings to dry. In about two 
weeks after this the females commence de¬ 
positing their eggs. From personal observa¬ 
tions, and all the data I have been able to 
obtain, it is found that the term of life of the 
individuals in their natural conditions, from 
the time the egg is deposited until the result¬ 
ing moth deposits eggs, is, on an average, 
about 77 days : egg, 14 ; larva, 30; pupa, 17 ; 
moth, until the female deposits, 16 days. 
The second brood of moths usually appears, 
in this region, in the latter part of June. 
Their history during the remainder of the 
year, in their natural conditions, is not so 
thoroughly known as that during the first 
half. By a wise provision of nature, it is so 
managed that an excessive multiplication of 
the species necessarily exposes them to view, 
and thereby brings upon them an excessive 
nnmber of parasitic insects. The consequence 
is that a numerous second brood of “ worms ” 
is an anomaly. I have observed but one fall 
“army” during thirty years’ observations, 
and know of only two well attested cases of 
the kind in this immediate section in that time. 
That the species is two-brooded here we know 
from direct observations ; and that the pupse 
of the second brood occasionally develop into 
moths, in the fall, is also an established fact, 
but all the data obtainable show that this is 
the exception and not the rule ; and that on 
the contrary the mass, in fact, nearly all of 
the pupae of this second brood remain in this 
state over the winter, coming out as moths 
about the first of April. Some experiments 
made, and others now being made, indicate 
that in confinement the moths of the second 
brood usually hatch out, whereas, in their 
natural condition, the rule is just the reverse, 
as above stated. Whilo the proof is conclu¬ 
sive that in this locality they hibernate in the 
pupa state, there are strong reasons for be¬ 
lieving that a different rule prevails in the 
extreme northern part of this State, and also 
in New York. The determination of this 
point for the different localities is of some 
importance, as on it depends, to a certain 
degree, the value of some proposed remedies. 
One important fact in reference to their 
development is, that they do not appear in 
excessive numbers except in a spring follow¬ 
ing a dry season. This is important, because 
it enables the farmers to predict* vhen it will 
not appear, though they may not be able to 
tell beforehand when it will. 
Experience since 1844 appears to demon¬ 
strate conclusively that another requisite, at 
least in this section, is, that the spring in 
which they appear shall be damp, or at least 
cloudy and rather cool. The year, on the 
whole, may be more than ordinarily dry and 
warm, but the spring must be damp and cool 
in the localities where they appear. But few 
if any exceptions can be found to this rule ; 
in fact hot, dry weather will soon cause them 
to disappear. It is a fact worthy of notice, 
that in Illinois the Army Worm has appeared 
in the spring following each Chinch-bug year. 
Remedies and Precautionary Measures. 
That it is possible to protect a field from a 
marching army of worms by ditching, is a 
well-kown fact. Planks placed on edge and * 
fitted end to end, smeared on the upper edge 
with coal tar or kerosene, is another method 
which has been adopted in some cases with 
success ; placing lines of coal tar across their 
pathway has been tried, but they soon 
cover this and pass over it. Sprinkling the 
grass in front of them with water mixed with 
Paris Green and London Purple has, it is said, 
proved successful in checking their march; 
but the use of such poisonous substances in 
such places cannot be justified and should 
never be adopted. Where the worms have 
obtained possession of a field, and spread 
themselves over it, there is no practical way of 
destroying them, and at the same time saving 
the crop. Topical applications, such as solu¬ 
tions, powders, etc., are utterly useless and 
a waste of time and money, except so far, 
only, as they act as fertilizers. Running 
heavy rollers of stone or iron over the field 
has been suggested, but the objections to this 
plan are, that comparatively few farmers are 
supplied with such rollers, and that only a 
portion of the “worms” are destroyed by 
this means. Where it is very desirable to pre¬ 
serve the meadow so far as possible, this plan 
is worthy of adption by all who may be pre¬ 
pared for it. Burning over the meadows in 
the winter or early spring has proved, in some 
instances, an effectual remedy in this lati¬ 
tude, probably because it destroys the old 
grass in which they prefer to deposit their 
eggs. The chief objection to this remedy is 
that it requires the burning to be done every 
year, unless some means of knowing before¬ 
hand when the insects will come can be as¬ 
certained. As we already know that they 
only come after a dry fall or summer, this 
will limit the use of this precautionary meas¬ 
ure to the winter following such seasons. 
My own opinion is, that if the “worms” 
are very numerous in a meadow, the best 
thing that can be done is, to turn them under 
with the plow as deeply as possible, and plant 
the ground in some crop that can bo matured 
in the season, and that is applicable. If the 
meadow is new, and it is very desirable to 
preserve it for the next year, the farmer must 
then turn in hogs, etc., use the roller, or 
adopt such device as may be most convenient 
so as to make the injury as light as possible, 
but with no idea of saving the present crop. 
