OBSTRUCTIONS TO DEVELOPMENT 127 



Wireworms injure potatoes by boring through them. 

 They are more prevalent on land which has been in 

 grass a few years. Frequent rotation and fall plowing 

 are advised for both of these pests. 



Other insects injurious to potatoes include: Striped 

 Blister Beetle, or ' ' Old-fashioned Potato Bug ' ' (Epi- 

 cauta vittata). This insect should be combatted in the 

 same way as the Colorado potato beetle by applica- 

 tions of arsenical poisons to the foliage. The Tomato 

 Worm and Cutworms are injurious. The latter are 

 very destructive at times, and the best remedy seems 

 to be to place bait, made of moist bran and sugar, 

 poisoned with Paris green in the fields. 1 



Arsenical Poisoning. Paris green, London pur- 

 ple, and other arsenical compounds usually carry their 

 arsenic, in an insoluble form, but some may be soluble. 

 This soluble arsenious oxide may burn the leaves, espe- 

 cially the tips where the mixture flows, and the edges 

 of mutilated leaves, causing death of the spot and a 

 ' ' target-like ' ' appearance of the leaf. 



Remedy. Do not use more than i pound of Paris 

 green per acre, dissolved in 100 to 200 gallons of Bor- 

 deaux mixture. The trouble is most prevalent where 

 people half spray and use Paris green alone, or i 

 pound of Paris green in one barrel (50 gallons) of 

 water and lime or Bordeaux mixture. 



1 N. J. Bui. 109; Report, 1895, p. 366. 



