200 THE CANADIAN ENTOMOLOGIST. 



Antennae, legs, and most of the under surface, excepting the sides of the 

 prothorax, black. It is found both in America and Europe, and has 

 here gained an additional importance through its destructiveness to 

 turnips, radishes, and cabbages in the Western Provinces. 



Prasocuris, Latr. 

 Elongate species of less convex form than usual, upper surface 

 striped with yellow and brassy-green or bronze-black. The three species 

 are thus separated by Mr. Crotch : — 

 Each elytron with two yellow vittae not confluent at base. .24 



in , phellandrii^ Linn. 



Yellow vittas of elytra confluent at base. 



Legs black. . [8-. 2 2 in obliquata, Lee. 



Tibiae pale ( — varices, Lee). .14-. 18 in vittata, Oliv. 



DORYPHORA, 111. 



Contains two large species of robust and convex form and bright 

 colours. D. decenil'meata, Say, the " Colorado potato-beetle," is almost 

 too well-known to need a description — its yellowish colour, with black- 

 spotted thorax and the five black stripes (the second and third of which 

 are united at tip) on each elytron, rendering it easily recognizable. D. 

 clivicollis, Kirby, is found on milkweed, and reaches a size of from .32 to 

 .48 in. It is of a dark blue, the elytra orange-yellow, usually with three 

 black spots on each, arranged thus : One on the humerus, one near the 

 apex, and one on the suture, confluent with its fellow on the opposite 

 elytron. The spots may all become confluent laterally, thus forming two 

 broad blue bands, or, as in the variety Rogersii, Lee. (which is described 

 as having the sides of the thorax nearly parallel behind), may become 

 very much reduced in size and break up into numerous smaller ones. 



Chrysomela, Linn. 



The species of this genus are more numerous and usually smaller 

 than those of Doryphora, to which they bear a general resemblance. 

 They are usually taken by sweeping. I find C. exclamatiojiis on 

 Helianthus, while C. elegans is occasionally abundant on willows. The 

 following table will enable the Canadian species to be separated without 

 much trouble : — 

 A. Elytra with tolerably regular stripes, never with numerous spots, 

 b. Front and side margins of prothorax pale, sometimes the base 

 also, 



