196 



STATE BOARD OF AGRICULTURE. 



Some years ago, Mr. E. G. Lodeman, then of Cornell University Experi- 

 ment Station, discovered that potatoes sprayed with bordeaux mixture 

 for the blight were avoided by the beetles. This led to some experi- 

 ments which showed that a number of flea-beetles were repelled by the 

 bordeaux. Use the ordinary mixture, the formula for which is given 

 on another page of this bulletin, and add one-fourth pound of paris- 



Fig. 46. — Colorado potato beetle. (After Walsh and Riley, American Entomologist.) 



green to each fifty gallons of the mixture. The paris-green kills some 

 of them and incidentally many other chewing insects. The cost of 

 the paris-green is insignificant when compared with that of preparing 

 and applying the bordeaux. 



Potato-beetle (Leptinotarsa 10-lineata). 



Pre-eminent among potato insects stands the Colorado potato-beetle. 

 So familiar is this pest that no description is necessary, either of the 



yellow and black beetle with the ten 

 longitudinal lines on the back or of the 

 reddish-brown larvae that occur in 

 such numbers on neglected potato 

 plants. Up to the middle of the nine- 

 teenth century, this beetle was content 

 to feed on weeds belonging to the po- 



#^H^ tato or nightshade family in Colorado, 



^^^ft but as farming progressed westward, 



^^w the more choice and acceptable Irish 



^it^ potato reached the region inhabited by 



the beetle. The result was like spread- 

 ing straw slowly up to a bonfire. When 

 it once started, the spread was most 

 rapid, the beetles invading more and 

 more territory until now we expect to find the beetles wherever we find 

 the potato. 

 The life history of this pest is quite simple, — the eggs are laid in 



Fig. 47. — Eggs of parasitic fly (Phnrocera 

 dnryphnrae), on potato beetle. Author's 

 illustration.) 



