18 



tioiis each year; the lir^t alxnit I lie muldlc ol' May, tlio second during 

 the latter part of June, and the third in August and vSeptember. liut one 

 of these generations is seriously injurious during the same year, some- 

 times the first and sometimes the second, Avhile the third, with rare 

 exceptions, is economically insignificant. The earliest generation (May 

 and early June) is most likely to be the destructive one in southern 

 Illinois, and the second generation (late June and early July) in the 

 cciiti-al and northern jmrts of the State. The third generation (August 

 and September) has never been injiu'ious, to my knowledge, in Illinois, 

 but has sometimes been so in New Jersey and New York. The al)un- 

 dant generation moves in hordes or " armies " out of its breeding grounds 

 and into adjoining fields, destroying virtually every green thing as it goes. 



Dcscn'plioii of the Ai-my-ivorni (See PI. II). — This cateri)illar has 

 the general ai)iiearance of a cutworm, to which, in fact, it is closely 

 related, antl whose habits and injuries to vegetation it imitates in ordi- 

 nary years when it is not unusually abimdant. It is readily distin- 

 guished, lH)we\er, from ordinary cutworms by its nuich more distinctly 

 striped markings, in colors ranging from light greenish yellow to greenish 

 black and black, iiooking at the side of the caterpillar, one sees three 

 such stripes very distinctly marked, of which the central one is dark, 

 and the others are lighter. The back of the cater})illar is greenish black, 

 and along the middle of it runs a narrow white stripe, broken and usually 

 indistinct except at vixvh. end. Of the three side stripes, the lower one, 

 which is just below the spiracles, is light greenish yellow and is narrowly 

 edged with white. The upper one is a little darker, also etlged with 

 white, autl with its center greenish black. The middle one of these three 

 stripes, which has the spiracles at its lower edge, is black, sometimes a 

 little lighter along its center. The head is of a greenish brown color, 

 with coarse black mottlings, and with blackish lines where the pieces of 

 the head seem joined together. The belly of the larva is lighter than 

 the back and more or less mottled with blackish. This description 

 applies quite closely to ortlinary examples, which the colored plate in 

 this report correctly- illustrates. Sometimes, however, paler specimens 

 are found, in which all the colors are less intense, but the pattern is 

 unchanged. 



The Armij-worm Moth (See PI. II). — The army-worm hatches from 

 eggs laid by very common night-flying moths. These are yellowish 

 brown, with a white speck near the middle of each fore wing, as shown 

 distinctly in the colored plate. They are fond of sweets, and may be 

 captured in large numbers at night by using sugary substances as a bait. 



Ilobits of the Army-worm. — Army-worms are present every year, anil 

 are among the most numerous of our native insects. When present in 

 only ordinary numbers they feed singly in grass-lands like cutworms, 

 remaining hidden during the day, and are then little likely to be seen. 



