804 Journal of Agricultural Research vol. vi, no. 21 



It will be noticed that the egg stage approximated 6 days, the larval 

 stage required about 26 days, and the pupal stage 21 days for over 100 

 individuals and that the average length of life cycle for these was 53 

 days. It will also be noticed that for the cages kept indoors, which 

 would approximate late spring, summer, or early fall conditions, the total 

 length of the larval period averaged about 23 days; that of the pupal 

 period about 17 days, and that of the entire life cycle approximately 47 

 days; while for the individuals kept on the back porch, which approxi- 

 mated early spring or late fall conditions, the average length of the 

 larval period was about 3 1 days, the pupal period 30 days, and the 

 total life cycle approximately 68 days. The larva has six instars, 

 molting five times previous to pupation. However, this may vary, for 

 among the 107 individuals reared through to the adult stage one had 

 seven instars, molting six times. 



In the outbreak in Michigan, which claimed attention in the latter 

 part of July, 191 4, oats, barley, corn, grass, alfalfa, and beets were at- 

 tacked in the order mentioned. Oats and barley were backward on 

 account of an unusual June freeze and for this reason were more succulent 

 and attractive to the army worms. In the case of small grains, especially 

 oats, the relative amount of injury was much greater in proportion to 

 the amount of actual food eaten than for such crops as corn, for in the 

 former case the grain was clipped from the stalks by the worms, leaving 

 most of the grain uneaten and the ground whitened with the grain heads. 



At the time of the outbreak mentioned above the corn was 2 feet in 

 height. Montgomery * has shown that mature corn plants have a 

 foliage area of 927.8 to 1,912.9 square inches, with an average of 

 1,200 square inches. Corn plants 2 feet in height would have at the 

 most not more than one-twelfth the foliage area of a mature plant; hence, 

 it can be said with comparative assurance that a corn plant such as 

 was found in Michigan during the 1914 outbreak would have not more 

 than 100 square inches of foliage. Since one larva would eat 41.4 

 square inches, it would require five larvae to devour two corn plants. 

 With 8,890 corn plants to an acre (2^ plants to a hill and sH feet 

 each way), it would require 21,473 worms to destroy an acre of corn 2 

 feet in height. Although seemingly a large number of worms, this 

 number represents only the progeny of probably not more than 40 

 female moths. 



According to the observations of the writers, the eggs laid at night in 

 clusters of 25 to 134 on grass or other host plant between over- 

 lapping leaves fastened together or between the leaf sheaths, often 

 none of the eggs or only a small part of the mass being visible 

 (PI. CVII, B). They are fixed to the leaf by means of a glutinous secre- 

 tion which when dry is white and flaky. The largest number of eggs 

 laid by a single female was 254 (see Table II), and in all cases where 



'Montgomery, E. G. Correlation studies of corn. In Nebr. Agr. Exp. Sta. 24th Ann. Rpt., 1910, p. 

 108-159, illus. 19"- 



