224 INSECTS INJURIOUS TO VEGETABLES 



This weevil is subject to the attack of a small four-winged 

 parasitic ichneumon fly, Sigalpliiis curculionis Fitch (fig. 143), 

 a well-known enemy of the plum curculio, and sometimes it 

 falls a prey to wireworms. 



Remedies. — The best remedy is to pull infested vines as soon 

 as they wilt and show evidence of attack, and spread them out 

 so that they will be exposed to the sun and will dry and thus 

 prevent the escape of the insects which they contain. All stalks 

 in infested fields should be burned as soon as the crop is off. 

 This will greatly lessen the number of weevils for the ensuing 

 years. It is also advisable to keep down all solanaceous weeds. 

 The time for their destruction is in July, after they have at- 

 tracted the beetles for G^gg laying, or any time before the seeds 

 are ripe. The use of fertilizers will often aid. injured plants to 

 recuperate from attack. Unfortunately, injury is not apt to be 

 detected until the plants begin to die. As soon, therefore, as 

 a plant shows weakness its stalk should be split open to ascertain 

 the cause. Early potatoes are most subject to injury, and the 

 latest varieties are practically exempt. 



The Potato Tuber Worm (PhthoriuKra opcrculclla Zell.). — 

 The tuber worm is probably the most injurious insect to the 

 truck industry of California, where losses to the potato crop 

 have been estimated as aggregating some years 25 per cent. In 

 Salinas Valley, dealers claim that at times the loss has gone 

 as high as 40,000 sacks a year. Potatoes from other sections 

 have to be watched carefully to • avoid "wormy" ones, as a 

 very few such may infest a whole storeroom. As the potato 

 is a product that is expected to retain its value for months, the 

 possibility of destruction by insects while in store becomes a 

 question of great seriousness, more particularly because rots 

 follow the "worm," starting in its burrow and ultimately in- 

 volving the entire tuber. Although the species is introduced 

 and rather commonly distributed in temperate portions of the 



