2 BULLETIN 535, U. S. DEPARTMENT OF AGRICULTURE. 
Koch.t It was obtained for the first time in 1893 on the withered — 
leaves of horse-radish in a vacant lot within a fourth of a mile of the 
erounds of the Columbian Exposition at Chicago, Ill. It is possible 
that the species was actually introduced at about that time, but 
probably the time was one, two, or more years earlier, and it was not 
reported as a pest until 1908. 
The larve as well as beetles live on the leaves and petioles of 
the common horse-radish ([Vasturtiwm]| Radicula armoracia) and 
when numerous injure the plant to such an extent as to reduce 
materially the root crop. The larve mine the petioles or midribs 
(fig. 2), while the adults feed on the leaves, causing the charac- 
teristic flea-beetle injury—withering and dying—or gouge deep pits 
in the petioles or midribs. 
This beetle belongs to the same genus 
as the well-known injurious striped 
cabbage fiea-beetle (Phyllotreta vittata 
Fab.) but may be distinguished readily 
from all other species occurring in 
this country by its elytra or wing- 
covers, which are mostly of a pale 
cream color with a comparatively nar- 
row sutural black stripe, as shown in 
figure 1. 
The horse-radish flea-beetle, having 
recently become an economic factor 
in the growing of horse-radish? on a 
commercial scale in Brown County, 
near Green Bay, Wis., the junior 
author has been able to trace its life 
Fic. 1.—The horse-radish flea- : 
beetle (Phyllotreta armoraciae): economy and history. It first appeared ~ 
Adult. Greatly enlarged. (Origi- 
oar in sufficient numbers to be seriously in- 
jurious in the summer of 1914, when it 
was reported and observed by Prof. J. G. Sanders. In the two years 
following, the beetles reappeared in large numbers in the same 
locality. 
While as yet not very generally distributed and confined to 
attacks on the relatively unimportant crop of horse-radish, the pos- 
sibility that this insect in its new domain may adapt itself to the 
other and more important members of the cultivated cruciferous 
plants renders it worthy of such notice as can be supplied. | 
1 Order Coleoptera, family Chrysomelidae, subfamily Ialticini. 
2 The authors desire to acknowledge the cooperation of the Department of Economic 
Entomology, University of Wisconsin, and the many favors received from Mr. George B. 
Smith, Green Bay, Wis., on whose farm the junior author was stationed when many of 
the data in this paper were obtained. 
