ENTOMOLOGY 175 



The Stalk-Borer. This well-known caterpillar, often called the 

 heart worm because of the character of its injury to corn, may be at 

 once known wherever it is seen by the peculiar break in the striping 

 of the body at the middle. It is about an inch long when full grown. 

 The general color varies from purplish brown to whitish brown, ac- 

 cording to age, and it is marked with five white stripes, one running 

 down the middle of the back, and two on each side. These side 

 stripes are interrupted, being absent on the first four segments of the 

 abdomen, giving the larva an appearance as if it had been pinched 

 or injured there. The stripes nearly vanish as the larva matures. 

 The head and top of the neck, and the leathery anal-shield at the 

 opposite end of the body are light reddish yellow, with a black stripe 

 on each side. 



Its presence in a young stalk of corn is very clearly indicated 

 by the wilting, breaking down, and death of the top, and by the 

 presence of a round hole in the side of the stalk, plugged with the 

 brown excrement of the caterpillar within. 



It infests a great variety of other plants in a precisely similar 

 way. It is most noticeable in early spring in blue-grass, by road- 

 sides, or around the borders of a field, its presence there being be- 

 trayed by the whitening of single heads of the grass while all the rest 

 of the plant is green. At this time it is of small size, and finds 

 sufficient food within the grass stem ; but later it is compelled to re- 

 sort to thicker-stemmed plants, and it is at this time that it may ap- 

 pear in fields of corn. (Bui. 95, 111. Agr. Exp. Sta.) 



Going in usually from outside the field, its injury is, as a rule, 

 almost wholly confined to the outer rows. It rarely does any serious 

 general damage to corn, and it has also been occasionally found in- 

 juriously abundant in fields of wheat. It is probable that where 

 the injury is not limited to the margins of the field, but is general 

 throughout its area, the eggs were laid in fall in grass or thick- 

 stemmed weeds in corn-fields, where these have sprung up profusely 

 after the corn has been laid by. The burrow which the stalk-borer 

 makes within the stem runs upwards from the entrance opening, and 

 of course varies in size with the growth of the larva. Sometimes in 

 leaving a stalk it makes a new hole above that by which it. entered, 

 and it may in this way burrow in succession several different stalks 

 and several different kinds of plants. Corn is injured by it while 

 from two to ten inches high. 



It is only one of several insects which produce this general 

 effect at this time, but its own injury may be at once distinguished 

 by the round hole which it leaves in the stem of the infested plant. 



The caterpillar, when full grown, pupates, as a rule, within its 

 last burrow, commonly below the opening at which it entered 

 seemingly a precaution against its destruction by the withering and 

 breaking away of the upper part of the injured plant. The pupa 

 is light mahogany-brown, about three-fourths of an inch in length, 

 and bears at the tip of the body a pair of spines. From it comes out 

 a fawn-gray or mouse-colored moth, with the outer third of the 

 wings paler and bordered within by a whitish cross-line. Other 



