GRAPEVINE FLEA-BEETLES. 21 



considerable damage by its skeletonizing of the foliage. In one 

 instance the writer has noted the killing of 1-year-old vines of the 

 Delaware variety by repeated defoliation. Not the least important 

 economic consideration with regard to this beetle is the possibility 

 of its being mistaken for the larger form and the consequent con- 

 fusion of remedial measures. 



In spite of their potential ability to injure the grape industry, dur- 

 ing the years of the writer's residence in the Erie-Chautauqua grape 

 belt (1914-1917) both of these insects were of minor importance. 

 Such infestations as were observed were confined to vines on the 

 borders of vineyards adjacent to woodlands in which there were 

 heavy growths of wild grapes. 



The grapevine flea-beetle, like a number of related insects, is 

 given to sporadic outbreaks of destructiveness followed by periods 

 of comparatively little economic importance. This is well illustrated 

 by the periodic receipt of complaints by the Bureau of Entomology. 

 Based on this source of information, it appears that there have been 

 three distinct extensive outbreaks in recent years: One in 1892 in 

 Michigan, Missouri, Iowa, and Kansas, one during 1894 and 1895 in 

 New York, and one in 1911 in Maryland, Virginia, and the District 

 of Columbia. Requests for information regarding this insect have 

 been received in practically all of the intervening years, but they 

 have been comparatively few in number and much more local. 

 Slingerland (19), writing in 1898, also records a serious period of 

 destructiveness in New York for several years previous. On the 

 other hand, 17 years later Hartzell (24) estimated that in the Erie- 

 Chautauqua grape region less than 1 per cent of the area was infested. 



It is probable that the period when the writer's observations were 

 made represented a low tide in the abundance of these beetles, due 

 to natural checks, as they were totally absent not only in vineyards 

 where measures to destroy them might be taken, but also from the 

 majority of neglected vineyards and from most growths of wild 

 grapes. But aside from the natural causes there are two other fac- 

 tors which have contributed to a permanent change in the economic 

 status of this pest. Poison sprays, applied primarily to destroy the 

 grapevine rootworm (Fidia viticida Walsh) and the grape-berry moth 

 (Polychrosis viteana Clem.), readily destroy the flea-beetle larvae feed- 

 ing on the leaves at that time and may destroy many of the adults 

 of the lesser flea-beetle which are also still in the vineyards. Up-to- 

 date methods of tillage under vines, which break open the pupal 

 cells, are also a contributing factor. These two factors make it diffi- 

 cult for beetles to reproduce in well-cared-for vineyards and limit 

 them to neglected vineyards and wild vines. Sporadic outbreaks 

 may nevertheless be expected in vineyards adjacent to favorable 

 breeding places, and these may be very severe locally. 



