27 



In the more southern part of the Transition zone the insect is nota- 

 bly niore successful, though nowhere in this zone is it a pest of regular 

 occurrence or of any considerable importance. In Massachusetts it 

 was reported as quite abundant in 1894, and its presence had been 

 noted in sweet corn several years previously in certain of the smaller 

 towns in the neighborhood of Boston. It would appear, however, that 

 the bollworm becomes thus numerous at rather long intervals. Accord- 

 ing to Doctor Fernald (in lit.) only three examples were received by 

 him at the Massachusetts Experiment Station from 1899 to 1904. 



In Michigan, which is largely within the Boreal and Transition 

 zones, the bollworm is also of comparatively rare occurrence in inju- 

 rious numbers. Thus Mr. Tyler Townsend states^ that the species 

 came under his observation only once during a period of fourteen 

 years, namely, in 1881, when the larvae were frequently found in ears 

 of green corn. In Minnesota, according to Doctor Lugger,* the 

 insect does not winter, all individuals being killed in late fall, thus 

 necessitating their reintroduction each year. In commenting upon 

 this statement Doctor Fletcher remarks that it is his opinion that 

 some of the insects, at least, hibernate in Canada as pupse. 



The almost total absence of references to this species in experiment 

 station and other literature from the Dakotas, Montana, Wyoming, 

 and Washington indicates its comparative scarcity, at least as a pest. 

 In a recent letter Prof. Avon Nelson states it as his belief that the 

 bollworm does not occur in Wyoming^; Professor Cooley does not 

 know of its presence in Montana; while Prof. W. H. Lawrence 

 advises that according to his information it does not occur in Wash- 

 ington. It is, however, reported from Idaho and Oregon. The 

 absence of sufficient data will, however, preclude the consideration of 

 the zonal distribution and destructiveness of the bollworm throughout 



this region. 



UPPER AUSTRAL ZONE. 



By reference to the map (PI. II) it will be seen that the Upper 

 Austral zone covers a large part of the more central territory, east 

 and west, of the United States. This zone is divided into two sub- 

 divicions, namely, the Carolinian area and the Upper Sonoran area. In 

 the present discussion it is necessary to consider them separately. 



CAROLINIAN AREA. 



The Carolinian area is distinguished from the Upper Sonoran by 

 reason of its greater humidity. It finds its western limits along the 

 one-hundredth meridian. Throughout practically all of this area the 



« Insect Life, II, p. 42. 

 ^Bul. 43, Minn. Agrc. Exp. Sta., p. 198. 



<^ Mr. E. S. G; Titus, of this Bureau, however, reports that he has taken the boll- 

 worm in Wyoming. 



