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 noi 
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 Wesl that the eastbound macropterous tide of migration found 
confronting it in Illinois, 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 tide- of migra- 
tion have met in northeastern Ohio ami 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 
OCClir in Central and North America are indicated. 
The writer believes that this same course of migration has been 
pursued, at least in the AYest, by the several species of Diabrotica, 
and especially 1>. longicornis Say. and to a les^ extent by another 
species of Hemiptera, Murgantia histrionica Ilahn 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 lias been followed in all probability by Pontia rapa 
L., Phytonomus j>nn<-t<itus Fab., Hylastinus <>l>s<-tii-us Marshm., and 
Crioceris asparagi L., 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 
Wesl Indie-, 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 -J .000 feet. Gen- 
erally its habitat is 1 .ooo or lower. The altitude where it was 
found breeding on Yolcan 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 ii.000 feet, 
while in Colorado it occurs sparingly near Fori Collins at an eleva- 
tion of 5,500 to 6,000 feet, while Professor Cockerel] did not find it at 
all in the -nine State at elevations of 7,000 to 8,000 feet. On Mount 
Washington, in New Hampshire, it ha- been found only once, and this 
