6 BULLETIN 535, U. S. DEPARTMENT OF AGRICULTURE. 
ORIGIN AND DISSEMINATION. 
The horse-radish flea-beetle is of European origin, and was first 
described by Koch in 18031 from Germany. . It is a well-known 
species in the Old World, and its specific name is derived from its 
favorite food plant (Vasturtium) Radicula armoracia. Like all of 
the striped flea-beetles of the true genus Phyllotreta, the present 
species breeds on cruciferous plants. 
As to the means of introduction of this species in the heart of this 
country, 1t was probably brought in with horse-radish and less prob- 
ably in marsh cress (fadicula palustris), or possibly with some 
potted plant. It is not impossible that these plants were brought to 
America expressly on account of, if not actually for, exhibition at 
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Fic. 6—Map showing present known distribution of the horse-radish flea-beetle. 
(Original.) 
the Columbian Exposition. It is remarkable, however, in being 
introduced, not near a seaport, but so far inland. 
In the ‘es of its nativity this species ranges throughout middle 
Europe. Among early records of its establishment in the United 
States are Guttenberg, Iowa; Chicago and Bloomington, Il.; and 
Okauchee, Wis., about 30 miles due west of Milwaukee, and in 1896 
there was a strong probability that it would soon spread to Missouri 
end perhaps to southern Minnesota and Michigan—in other words, 
that it would establish itself in the course of time in the upper Aus- 
tral and, perhaps, a portion of the Transition region in the vicinity 
of its known range at that time. This would include Nebraska in 
the West and Ohio in the East. The natural progress of most in- 
sects introduced from Europe is westward, but there are several 
1 Numbers in parentheses refer to ‘‘ Bibliography,” p. 15. 
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