THE GRAPE ROOT-BORER. 27 



As the larvae increase in size the burrows become large and irregu- 

 lar in outline, and roots that are half an inch or less in diameter 

 usually are eaten off or injured so severely that the outlying section 

 dies. Very large roots may withstand the combined attacks of 

 several borers without being killed. Such large roots are usually 

 eaten most extensively along the underside. 



The larva passes the winter in a roomy chamber at the end of its 

 burrow, the chamber being sometimes, although apparently not 

 always, lined with a very thin web of silk. Feeding is not continued 

 through the winter, but is resumed as soon as the soil becomes warm 

 in the spring. 



When full grown the larva makes an open passage from its feeding 

 place upward through the soil to the surface of the ground, where the 

 cocoon is constructed. The larva in some way transports from the 

 root considerable frass for use in making the cocoon. Evidently 

 after the cocoon is begun the larva passes back and forth frequently 

 from the cocoon to the root, probably feeding on the root at intervals 

 and voiding the frass while working at the cocoon. Pupation takes 

 place in June and early July. 



NATURAL ENEMIES. 



No parasites of this species are known. During the present in- 

 vestigation ants were seen carrying the moth eggs, but what disposi- 

 tion they made of them was not observed. In a previous study of 

 this species (8) the writer found the larva of a firefly beetle (PJioturis 

 pennsylvanica De Geer) which had broken into a root-borer cocoon 

 and was devouring the pupa. The crested flycatcher (Myiarchus 

 erinitus) was observed to catch several moths on the wing. 



METHODS OF CONTROL. 



This species does not lend itself readily to any of the common 

 insecticidal methods of control; neither is the worming process, so 

 often used against various borers attacking fruit trees, of practical 

 application against this species. The borers feed in the roots over 

 so wide an area that digging for them as a practicable method of 

 destruction is out of the question and even soil fumigants are, for 

 the same reason, of doubtful value. 



Thorough cultivation of the soil around the vines during June 

 and July is of some benefit in destroying the larvae and pupae in the 

 cocoons. By far the most valuable practice, however, is the applica- 

 tion of such cultural methods as would induce in a healthy vine a 

 vigorous and rapid growth. It was found that even badly infested 

 vines, when carefully pruned, sprayed, fertilized, and cultivated, 

 made a normal wood growth and bore satisfactory crops of fruit. 

 The borers, by killing the terminals of so many of the roots, greatly 



