316 



INSECTS INFESTING THE SWEET POTATO. 



Fig. 315. 



In this eountry there are no less than four different kinds of 

 tortoise beetles which are known to infest the sweet potato ; 

 they are more or less hemispherical in form, and the head is 

 concealed beneath a thin, transparent extension of the front 

 edge of the thorax. 



Fig. olo. — Mottled Tortoise Beetle, enlarged — color, black. 

 The two-striped tortoise beetle (CassicJa hivittaia — Say ; Fig. 

 812, 4,) is marked with two black strii)es on each wing-case. 

 In the three following species, the wing-cases are unmarked. 



The mottled tortoise beetle {('assida <ivtta1a — Olivier; Fig. 

 318,) has the shoulders bhickish to the extreme outer edge of 

 the wing-case. In the remaining two species the thin, transpa- 

 rent outer edge of the wing-cases and thorax is unmarked. 



Fig. 814. — Golden 

 Tortoise Keetlc and 

 Pupa : </, the l)eetle — 

 color, yellow; c, the 

 pupa — color. l)rown. 

 Fig. 815. — Egg of 

 (iolden Tortoise Bee- 

 tle, enlarged — color, dirty white. 



The golden tortoise beetle {Cnadda aari- 

 chalcea — Fabricius ; Fig. 814c/,) is of a deep c^, 



yellowish color, usually dotted with black, or 

 it is of a transparent golden color, shining like a drop of 

 liquid gold. It measures about two lines in lengtli. 



This is the only tortoise beetle tbat is known to occur in 

 this State, and is frequently met with on wild morning glories- 

 Fig. 81G.— Black-legged Tortoise Beetle- 

 color, yellowish. 



The black-legged tortoise beetle (Cassida 

 nigripcs — ( )livier ; Fig. 816) closely resembles 

 the last, but is larger, measuring nearly four 

 lines in length. It also differs in having the 

 legs l)lack, and each wing-case is marked with 

 three black dots. The larvte of these tortoise 

 beetles are elongate-oval in outline, greatly flattened, and have 

 a row of spines un each side of the body and two larger spines, 

 whieh are situated at the hind entl of the body ; these are usu- 



Fig. 316. 



