448 



INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



Distribution. — This moth is quite widely distributed, being reported 

 by county horticultural commissioners from the following counties: 

 Alameda, Contra Costa, El Dorado, Glenn, Kern, Los Angeles, Mon- 

 terey, Modoc, Napa, Nevada, Orange, Placer, Riverside, Sacramento, 

 Shasta, San Benito, San Bernardino, San Diego, San Joaquin, San Luis 

 Obispo, Santa Clara, Santa Cruz, Shasta, Stanislaus, Ventura and Yolo. 



Food Plants. — The following are hosts of this moth: cat-tail, egg- 

 plant, horse nettle, ground cherry, nightshade, potato, tobacco and 

 tomatoes. 



Fig. 457. — Cocoons and pupa of the potato tuber moth, 

 Phthorimwa operculella (Zell.), on potato. Natural size. 

 (Original) 



Control. — All host plants should be kept from growing in or around 

 the potato fields. Deep planting and hilling should be practiced to 

 prevent access to the tubers. The potatoes should be dug as early as 

 possible and not allowed to remain in the fields over night, unless sacked. 



In tobacco seed-beds the application of a spray composed of 1 ounce 

 arsenate of lead to 16 gallons of water has given good results. 



In places of general infestations the tubers may be thoroughly disin- 

 fected before storing, by soaking them in water for thirty-six hours. 

 This method is claimed by some shippers to ruin the potatoes. Heavy 

 fumigation (3 ounces of potassium cyanide per 100 cubic feet) has 

 been recommended to kill the larva? in infested potatoes, but even such 



