22 BULLETIN 901, U. S. DEPARTMENT OF AGRICULTURE. 



PREDATORY ENEMIES. 



The natural causes responsible for the periods of comparative 

 unimportance of the flea-beetles at the time they were under observa- 

 tion were undetermined. Three species of carabid beetles and one 

 of ants were found predatory on both flea-beetles, although none of 

 the carabids was found in large numbers. No species of parasites 

 has been reared by the writer. 



Lebia viridis Say, 1 the most common carabid, was closely asso- 

 ciated with both species of flea-beetles. It feeds upon the eggs, 

 larvae, and pupae of both species. This Lebia, although classed as a 

 ground-beetle, is largely arboreal. It was found in leaf mold under 

 wild grapevines, where flea-beetles were pupating in large numbers, 

 but more frequently on grape leaves, both in vineyards and on wild 

 vines. One specimen was taken on a wild grapevine over 15 feet 

 above the ground. In spite of their individual voracity, as these 

 beetles always occurred singly and were never found in large numbers, 

 they were not regarded as of sufficient importance to hold the grape- 

 vine flea-beetles in check. 



The earliest recorded collection of Lebia viridis was May 22, in 1917. 

 This beetle was found feeding upon eggs under strips of bark on grape 

 canes. ISo more were found until June 22, when larvae of the typical 

 flea-beetle were quite common on the vines. After this time until 

 the first of August Lebia viridis was fairly numerous. The latest 

 record of collection was September 11, in 1916, after all of the imma- 

 ture stages of the flea-beetles had transformed. 



This carabid is steel blue in color and about the size of the typical 

 grapevine flea-beetle, with which it might be confused by a casual 

 observer. It is probably the enemy of the flea-beetle referred to by 

 Hartzell (24), which he describes as a " carabid closely resembling the 

 adult flea-beetle in size and color." 



Lebia ornata Lee. 1 and Harpdlus eryihropus Dej. 1 were found in 

 very small numbers in leaf mold under wild grapevines, and fed upon 

 pupae and prepupae of the flea-beetles in confinement. 



A brown ant, Myrmica, scabrinodis Nyl., subsp. schencM Emery, 

 var. emeryana Fore!, 2 destroyed a large amount of larval and pupal 

 material that was intended for use in rearing work. Full-grown 

 larvae had been placed in earth in flowerpots partially buried in the 

 insectary yard. A few days later ants were found carrying larvae 

 and pupae from these pupation quarters. 



The Biological Survey has found grapevine flea-beetles in the 

 stomachs of the following birds: Bobwhite (Colinus virginianus) , 

 meadowlark (Sturnella magna), Cape May warbler (Dendroica tigrina), 

 red-eyed vireo (Vireosylva olivacea), white-eyed vireo (Vireo griseus), 



1 Determined by Mr. E. A. Schwarz. 2 Determined by Dr. W. M. Wheeler. 



