INSECTS INJURIOUS TO POTATOES AND TOMATOES 303 



Three-lined Leaf -bee tie * 



Closely related to the Colorado potato-beetle, and very 

 similar to it in habits, is the Three-lined Leaf-beetle. The eggs 

 may be distinguished by the fact that they are usually laid in 

 rows along the midrib on the under side of the leaf, while those 

 of the potato-beetle are laid indiscriminately in bunches. The 

 larvae, however, may be readily distinguished from all other 

 insects attacking the potato by being covered with a disgusting 

 mass of their own excrement. 



FIG. 220. Three-lined leaf-beetle (Lena trilineata Oliv.); a, larva; b, pupa; 

 d, eggs; beetle at right. (After Riley.) 



There are two broods during the season, the larvae of the first 

 appearing in June, and that of the second in August; but the 

 beetles' of the second brood do not emerge until the following 

 spring. In other respects the life history is practically the same 

 as that of the Colorado potato-beetle. The beetle is of a pale 

 yellow color, with three black stripes on its back, and in a general 

 way resembles the common striped cucumber-beetle (Diabrotica 

 vittata Fab.), though it is somewhat larger and the thorax is 

 decidedly constricted. 



In case it becomes necessary to destroy the blister-beetles, both 

 they and the three-lined leaf -beetle may be readily disposed of by 

 applying Paris green or other arsenite as advised for the Colorado 

 potato-beetle. 



* Lema trilineata Oliv. Family Chrysomelidce . 



