THE HORSE-RADISH FLEA-BEETLE. 8 
DESCRIPTIVE. 
THE ADULT. 
In appearance Phyllotreta armoraciae is distinct from any species 
of flea-beetle belonging to or introduced into this country. It is 
somewhat larger and wider than 
any of the native species of the 
Tents. wilt iis of .oval.dorm, 
strongly convex, and black in 
color. The first three antennal 
joints, the apices or tips of the 
four anterior femora, the tibie, 
and the tarsi are reddish yellow. 
The elytra are very light yel- 
lowish, or cream color, nearly 
white, with a very thin black 
lateral margin and a broadened 
sutural stripe, widest at the mid- 
dle and constricted at each end 
and extending from the base of 
the thorax to the apex of the 
elytra, where it joins the lateral 
line. The frons or front is very 
finely, and the prothorax and 
elytra densely, punctate. A 
sensitive pore from which pro- 
ceeds a seta is located on the 
lateral margin, which is behind 
the anterior angle. In the male 
the fourth antennal joint is 
shehtly thickened and longer 
than the fifth. In the female the : 
fourth and fifth joints are equal. Fig. 2.—Work of the horse-radish flea- 
The average length ig from 2 Aseajce petioles of horse-radish. 
to 3.3 mm., but individuals have 
been observed where there is a variation of from 2.6 mm. to 3.4 mm. 
and a variation in width of 1.3 mm. to 1.9 mm. 
The following synonymy is recognized : 
Phyllotreta armoraciae (Koch). 
Haltica armoraciae Koch, Entom. Hefte. v. 2, p. 75, 1803. 
Haltica vittata Steph., Mandibulata, p- 292, 1831. 
The species is also treated systematically by Illiger, Duftschmidt, 
Gyllhenhal, Schilling, Redtenbacher, Seidlitz, Foudras, ANard, Lees- 
berg, and others. 
