250 THE CEREALS IN AMERICA 



protect and care for the plant-lice in return for their secretions which they consume 

 They are held in check by carnivorous and parasitic insects. The corn root louse 

 does its greatest injury to the young maize plant during May and June, causing the 



plant to wither and die by sucking its juices. 

 Usually these attacks are in spots throughout 

 the field and are likely to be most injurious 

 during unfavorable weather conditions. The 

 injury done by these insects is variable and fit- 

 ful, owing, doubtless, to their great prolificacy 

 and the enemies which keep them in check, 

 so that remedial measures are usually of slight 

 avail. The corn plant louse (^Aphis maidis) 

 Corn root louse on the left and its care, attacks the plant above ground, but it appears 

 taker, the ant, on the right, both to be less injurious than the corn root louse, 

 enlarged. (After Forbes.) whose attacks are confined to the roots. 



334. Corn Bill Bugs. — Several species of bill bugs are known to be injurious 

 to maize. The adults are black beetles one-fourth to three-fourths inch long, which 

 do their damage by puncturing the stalks and the young leaves of maize as they 

 are unfolding. Eggs are usually laid during the spring and summer and reach the 

 pupal stage in about one month. In some species the larvae live in the interior 

 of the stalk, bulb or roots of small grain or timothy, and in other cases in the maize 

 plant itself. They pass the winter in the adult form. The damage is generally 

 comparatively slight. There is no specific remedy. 



335. Corn Ear- Worm. — The larva, one and one-half inches long, varies in 

 color from pale green to dark brown, is marked with longitudinal stripes of the same 

 color, with eight round shining black spots on each segment of the body from which 

 arise short hairs ; the head and neck are brown. It is two to seven-brooded, depend- 

 ing upon the latitude. The last brood passes the winter in the pupal stage, emerging 

 as a moth in the spring. In the Northern States the most destructive brood lays 

 its eggs in the silk when the ears are young, and the larvae feed upon the grains at 

 the tip of the ear, often doing great damage, not alone on account of the grain 

 actually eaten, but also through subsequent decay by access of moisture and through 

 destruction due to other insects. In the Southern States the earlier broods are also 

 destructive by feeding upon the leaves and stalks. This insect is injurious to cotton 

 by feeding upon the bolls ; hence is known as the boll worm. Disturbance of the 

 pupa by late fall plowing or early spring plowing appears to be of some value, 

 although no remedy has been found which is entirely efiicient. 



336. Stalk Borers. — There are at least three species of insects which injure 

 maize by boring in the stem, although they are often equally injurious to other 

 plants, including weeds; namely, the stalk borer {Gortyna nitela Guen.), the smaller 

 stalk borer {Pempelia lignosella Zeller) and the larger stalk borer {Diatraea saccharalis 

 Fab.). 1 The most serious injury is usually done by the latter, which in the South 

 Atlantic States occasionally amounts to twenty-five to fifty per cent of the crop. 



\ y. S. Dept of Agr., Div. Ent. Cir. x6, 2d Ser. 



