DESTRUCTIVE INSECTS. 207 



but it usually becomes a serious one wherever it gets thor- 

 oughly established, especially in light soils. The wilting of 

 the vines, as if for want of water, is said to be an indication 

 of the presence of the insect on the roots. One should dig up 

 and carefully examine the roots of such wilted plants. If the 

 insect is found, the most stringent measures should be taken 

 to prevent its spread. 



It is said to be accompanied by ants, which may spread it 

 from plant to plant. It is spread into new localities oil the 

 roots of the plants sent out by dealers. 



Thus far, no one has succeeded in devising a practicable 

 method of killing the lice on the plants after they are set. 

 Some claim to have been successful with tobacco dust, but 

 others have failed. Badly infested fields had better be 

 plowed under at once and other crops grown there for a year 

 or more. The only sure way to avoid the insect is to buy 

 plants entirely free from it (doubtless plants which had been 

 properly fumigated with hydrocyanic acid gas would be safe 

 to use), and then set them on land where the louse has never 

 existed. 



The Strawberry-crou'n Borer ( Tylodernia jragaricz) is one of 

 the most destructive strawberry insects in the Mississippi 

 Valley. The adult insect is a small brown snout-beetle allied 

 to the plum curculio. It cannot fly, as its wings are rudi- 

 mentary. The female lays her eggs on the crown of the 

 plant in the spring, and the thick, footless, white grub which 

 hatches therefrom excavates the crowns during the summer. 

 In its subterranean cavity the grub transforms to a pupa, 

 and finally, in August and September, to the beetle, which 

 emerges from the crown, and, after feeding on the leaves, 

 hibernates in the strawberry field. Old fields are especially 

 liable to injury. 



As the beetles cannot fly, it is desirable to isolate the new 

 plantations from the old ones. If new plants must be taken 

 from an infested field, use those which started after July and 

 dig them early in the spring, to avoid carrying the eggs or 

 larvae of the insect with the plants. The plowing under of 

 the infested field about July ist will destroy the insect. The 

 frequent rotation of other crops with the strawberry patch 

 usually prevents the ravages of this crown borer. 



