28 



NEW YORK STATE MUSEUM 



acre. Conditions were so serious that 311 caterpillars were found in 

 one hill of corn, 117 in one stalk and 15 in one ear, one caterpillar 

 being sufficient to damage an ear seriously. The injury to nearby 

 field corn was nearly as great, though sweet com is much more 

 generally grown in the infested area. 



Food plants. There exists no undoubted evidence to show that 

 the European corn borer breeds in New York State in any plant 

 except com, though all varieties are subject to attack. The work 

 of the insect is most likely to be serious in small to medium varie- 

 ties of com because the larger ones can maintain a greater number of 

 borers with less likelihood of severe injury. It should be noted that 

 earlier fields of corn are much more likely to be infested than those 

 planted later. The principal food plants in Massachusetts, as shown 

 by investigations, are sweet corn, field corn, • fodder corn, celery, 

 beans, potatoes, Swiss chard, beets, spinach, dahlias, gladiolus, 

 chrysanthemums, and several of the larger stemmed weeds and 

 u/''N grasses, notably barnyard grass (plate 7) and the 

 common ragweed, or Roman wormwood. Some 

 of these plants become infested simply because 

 they are growing in or near infested corn fields, 

 though the pest seems to be able to maintain 

 itself upon barnyard grass, dock and lady's 

 thumb. The insect limits itself very closely to 

 corn in sparsely infested areas. 



Signs of infestation. The European corn borer 

 can be easily detected in corn stalks during the 

 winter by the characteristic holes about one- 

 eighth of an inch in diameter, frequently with 

 discolored margins and usually plugged with bor- 

 ings. These entrance holes (figure i) are most 

 easily seen on corn stalks which have been 

 stripped of leaves by cattle. The holes lead 

 into irregular burrows or galleries (plate 4, figure 

 2) I inch to several inches in length, each of 

 which is usually inhabited by a yellowish gray, 

 I. I Character- indistinctly lined caterpillar about three-fourths 

 holes in corn- of an inch in length. The head is brown, and 

 stalks as they occur ^^^ ^^^ minutely spotted with brown. The 

 m late summer, 



Fij 

 istic 



early fall and winter 



galleries that reach to the nodes are frequently 



iiTegularly enlarged at this point. The borer 

 also works in the stubble and may be found in com fields during 

 the winter. 



