CHAPTER XII. 

 INSECTS INJURIOUS TO THE POTATO. 



IXJURIXG THE TUBERS. 



Potato-scab and Insects. 



That certain forms of what is commonly termed '^potato- 

 scab" are due to the work of insects has frequently been 

 shown. In 1895 Prof. A. D. Hopkins, of the West Virginia 

 Agr. Experiment Station, reported some very careful orig- 

 inal investigations upon two species of gnats, Epidapns 

 scabies Hopk. and Sciara sp., the larv^ of which had been 

 conclusively shown to cause a scab upon the tubers bv 

 boring into them. He found that " they breed in and are 

 especially common in barnyard-manure," that ^'excessive 

 moisture in the soil has been observed to be the most favor- 

 able condition for their development," and that ''soaking 

 the seed-potatoes in a solution of corrosive sublimate 

 previous to planting" will kill all the eggs and youno- 

 larvae, as it will also destroy the spores of the potato-scab 

 fungus. 



Prof. A. H. Garman has also recorded the injuries of 

 "several species of millipedes, or "thousand-legged worms," 

 Camhala annidata and Parajulus impresstis, as causing a 

 scab by gnawing into the surface of the tubers. Though 

 both of these observations are unquestionably true, they 



