INSECTS. DISEASES, REMEDIES 67 



tent. Repeated applications are sometimes necessary 

 since poisoned beetles are replaced by others. 



Still another beetle which is particularly against 

 the bean industry in the Northwest is Nuttall's 

 Blister beetle (Cantharis nnttalli). The beetle is a 

 large and beautiful insect, variable both in color and 

 size. It is a bright, metallic green, with head and 

 thorax usually of coppery lustre, and wing covers 

 often purple. It varies in length from ^ to I 

 inch. The insect is particularly abundant in Colorado, 

 South Dakota, Minnesota, Montana, west Nebraska, 

 and northwest territories of Canada. It works very 

 rapidly and is noted for its sporadic attacks. Owing 

 to the rapidity with which it scatters havoc among 

 the bean fields, poisons cannot be depended upon, 

 Chittenden says stringent measures for the beetles' 

 destruction are necessary. They may be destroyed by 

 three methods : ( I ) By driving them into windrows 

 of dry straw and bunrt.g them ; (2) by spraying into 

 nets like those used by insect collectors and throwing 

 the captured insects into a fire; (3) by beating beetles 

 into safely prepared pans of water in which there is a 

 thin scum of coal oil. 



The Bean Ladybird (Epilachna corrupta), also 

 frequently referred to as the spotted bean weevil, has 

 been known for many years, but it has been found in- 

 jurious only for a few. It is nearly hemispherical, in 

 outline, broadly oval; its length is a little more 

 than % of an inch. Its color is light, yellowish 

 brown with four black spots on each wing cover. The 

 insect is often described as being one of the worst 

 enemies to bean crops in the West. In both larval and 

 adult stages it devours all parts of beans. The full 

 grown larvae shown in Fig. 20 is about the same length 



