70 THE CHINCH BUG. 
short- winged form predominates, but in hot, dry summers they mostly 
acquire fully developed wings. He had never found the species in 
grain fields of any sort, but always in grass lands, generally in timothy 
or clover, but sometimes in wild grasses. Of eleven specimens collected 
from under the bark of an old log by Mr. J. Pettit, of Grimsby, 
Ontario, in 1866, and sent to Mr. B. D. Walsh for determination, all 
were of the short-winged form.* It was these specimens that doubt- 
less led Dr. Eiley t to call attention to the fact that in Europe there are 
many genera of half winged bugs which occur in two distinct or 
" dimorphous" forms with no intermediate grades between the two, 
viz., a short winged or sometimes a completely wingless type and along- 
winged type. Frequently the two occur together and copulate pro- 
miscuously, while sometimes the long- winged type occurs in particular 
seasons, especially in very hot seasons, while more rarely the short- 
winged type occurs in a different locality from the long- winged type, 
and usually in that case in a more northern locality. In northeastern 
Ohio the species occurs during some years in great abundance and very 
largely at least on timothy. Here the short- winged form is very largely 
in the majority, and in the spring of 1897, of 1,900 specimens collected 
indiscriminately, only about 400 were of the long- winged type. 
In northern Indiana, where the insect occurs but rarely, I have also 
found this short- winged type, though I have not observed that it pre- 
dominates; but aside from these two localities, with an acquaintance 
with this species running over forty years, chiefly in Indiana and 
Illinois, I have never met with the short- winged type, though I have 
seen millions of adults. £ If this short- winged type occurs elsewhere to 
the westward, except along the Pacific coast, where both forms have 
been collected by Keobele and others, it has not been found by ento- 
mologists, even to the northward as far as Minnesota, Winnipeg, and 
Manitoba, while to the eastward of this Mr. Van Duzee collected the 
brachypterous form on Muskoka River, Ontario, near the lake of that 
name. § On comparing specimens from New York with a large series 
from Kansas, the former were found to be quite uniformly more robust, 
with longer hairs on the pronotum. || 
It seems to me that we here have evidence of two distinct tides of 
migration, the one sweeping north and eastward, while the other has 
mainly been to the north and westward, meeting the former in north- 
eastern Ohio and northern Indiana, and possibly somewhere farther to 
* Practical Entomologist, Vol. II, p. 21. 
t Second Report on tlie Insects of Missouri, p. 22, 1870. 
X Of a large number of adults collected late in April, 1898, while still in hibernation 
among the dead leaves in vineyards near the shore of Lake Erie, in northwestern 
Ohio, not a single brachypterous individual occurred, while of 66 specimens sent 
me from Salem, in northeastern Ohio, 50 miles from the lake shore, May 31, 1898, 
all but 6 were brachypterous, these latter being taken from a field of young corn, 
8 acres of which had been totally destroyed by them. 
§ Can. Ent. Vol. XXI, p. 3, 1889. 
||Loc. cit. Vol. XVIII, p. 209. 
