PROBABLE ORIGIN AND DIFFUSION. 89 
forests and prairies, and the stubble does not die with the harvesting 
of the crop as in wheat, and therefore annual migrations are not 
necessary for the bugs in order to preserve life. In a_ timothy 
meadow the species may live on and reproduce year after year with- 
out ever being obliged to abandon the field. It was the wheat fields 
of the West that the eastbound macropterous tide of migration found 
confronting it in Ilinois, and the smaller fields of grain and timothy 
meadows that the combined macropterous and brachypterous forms, 
more or less maritime and northbound, came in contact with along 
the Atlantic coast, while at the present time the two tides of migra- 
tion have met in northeastern Ohio and northern Indiana. 
In figure 17 is illustrated the theoretical directions and courses 
taken by each of these tides of migrations from the tropical regions, 
and in figure 1 the areas over which the species is now known to 
occur in Central and North America are indicated. 
The writer believes that this same course of migration has been 
pursued, at least in the West, by the several species of Diabrotica, 
and especially D. longicornis Say, and to a less extent by another 
species of Hemiptera, Murgantia histrionica Hahn and possibly also 
by Dynastes tityus L., while the two latter with others are now 
working northward along the Atlantic coast. Besides, the westward 
tide of migration has been followed in all probability by Pontia rape 
L., Phytonomus punctatus Fab., Hylastinus obscurus Marshm., and 
Crioceris asparagi 1, all of which have first become destructively 
abundant west of the Allegheny Mountains in extreme northeastern 
Ohio. The last four species, having been introduced from Europe, 
have undoubtedly migrated westward. 
With an almost total lack of natural enemies in the United States, 
and with nearly all of its closest allies belonging in Mexico and the 
West Indies, it would seem as though we were in possession of addi- 
tional evidence of the chinch bug’s tropical origin. Besides this the 
name “chinch bug” is of Spanish origin, and this language has 
never been in common use in North America except in Florida and 
the country along the Mexican border. 
The species certainly prefers the low country to the higher, and is 
seldom found in any numbers at an altitude of over 2,000 feet. Gen- 
erally its habitat is 1,000 or lower. The altitude where it was 
found breeding on Volcan de Chiriqui, in Panama, is 6,000 feet; and 
of its habitations in Guatemala, San Geronimo, is 3,000 feet; Panzos, 
2,000 feet ; Champerico, sea level, and Rio Naranjo, about 2,000 feet, 
while in Colorado it occurs sparingly near Fort Collins at an eleva- 
tion of 5,500 to 6,000 feet, while Professor Cockerell did not find it at 
all in the same State at elevations of 7,000 to 8,000 feet. On Mount 
Washington, in New Hampshire, it has been found only once, and this 
