66 BEAN CULTURE 



gregarious ; their habit in some seasons is to congre- 

 gate in great numbers, when, as they feed most vo- 

 raciously, they injure the crop in a few days beyond 

 recovery. The most troublesome Blister beetle in this 

 respect is familiarly known as the Ash Gray Blister 

 beetle (Macrobasis unicolor) a female specimen of 

 which is shown in Fig. 19. The beetle is elongate 

 in form, has a rather soft body of uniform ash gray 

 produced by a dense covering of minute hairs of this 

 shade. It inhabits the entire eastern United States, 

 over Canada, New England, and South Dakota to 

 Florida and Texas, and often extends westward to 

 Kansas and Nebraska. The beetles do severe injury 

 to beans by devouring leaves. In many instances it 

 has been found on cowpeas and Soy beans and also 

 on potatoes, tomatoes, etc. The larvae feed upon 

 grasshopper eggs, a habit which renders them of very 

 great aid in keeping these pernicious insects in check. 

 This is especially true in western states where both 

 Blister beetles and grasshoppers abound. However, 

 the harm they do overbalances the good, and in- 

 secticides should be used freely when they occur in 

 harmful numbers. Paris green is one of the best 

 remedies for this beetle. It may be applied dry, 

 mixed with 10 to 20 parts of plaster or air slaked lime 

 or in the form of a spray; also mixed with lime or 

 Bordeaux at the rate of Y^ pound of Paris green to 

 40 pounds diluent. Chittenden says that unfortunately 

 in the use of an arsenite upon beans there is difficulty 

 in obtaining a true mixture of the solution sufficiently 

 strong for the destruction of the insects without en- 

 dangering the plants by burning or scalding, though 

 the addition of lime mitigates this to a certain ex- 



