II. THE GRAPE ROOT-BORER. 1 



By Feed E. Brooks, Entomologist, Deciduous-Fruit Insect Investigations. 



CONTENTS. 



Page. 



Introduction. 21 



Economic history 22 



Geographical distribution 22 



Food plants 22 



Eecent injuries 22 



Nature of injury 23 



Page 



Description 23 



Activities of the moths 25 



Larval activities 26 



Natural enemies 27 



Methods of control 27 



Literature cited 28 



INTRODUCTION. 



The studies of the grape root-borer {Memyikrus polistiformis 

 Harris) described herein were conducted principally at French Creek, 

 W. Va., during the summers of 1916 and 1917. Conditions there 

 were favorable for the investigation, since the insect occurred abund- 

 antly and over a hundred badly infested grapevines were at the 

 entire disposal of the investigator. Wild grapes of the species Vitis 

 labrusca, V. cordifolia, and V. aestivalis abounded also in the locality, 

 affording an opportunity for observations as to native host plants. 



The grape root-borer in all its stages is peculiarly inconspicuous, 

 and there is a possibility that the species is a more widespread and 

 serious enemy of grapes than has been commonly supposed. The 

 eggs (PL III, E) are small and dark-colored and are so placed by the 

 female moth that they escape notice, the larvae (PL III, A, B) feed 

 exclusively on the roots and throw no castings to the surface of the 

 ground, pupation takes place within the soil, and the adults (PL 

 III, O, D) so closely resemble wasps of the genus Polistes that the 

 casual observer does not distinguish between them and true wasps. 

 Grapevines are rarely killed outright by the borers, but, on becoming 

 infested, usually linger for years, making meager annual growth and 

 bearing reduced crops of fruit (PL V) . There is a probability that 

 many vineyards suffer seriously from this insect while persons in 

 charge of the vines remain' unaware of the true cause of the trouble. 



Note. — The author wishes to acknowledge the assistance of Mr. C. R. Outright, 

 field assistant in the Bureau of Entomology, in conducting the investigation described 

 herein. 



i Memythrus polistiformis Harris; order Lepidoptera, family Aegeriidae. 



21 



