27 
In the more southern part of the Transition zone the insect is nota- 
bly more 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, namel}^, 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 pupae. 
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 scarcit}^, 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- 
divisions, namel}^, 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. 
c Mr. E. S. G. Titus, of this Bureau, however, reports that he has taken the boll- 
worm in Wyoming. 
