16 ALFRED E. CAMERON. 



on the roots of the tomato* and allied Solanaceous plants. The attack on the tuber 

 gives rise to a condition known as " pimply," formerly assigned to the activities of 

 the scab organism, the real cause having been discovered by Stewart ."j" The same 

 author {loc. cit.) says that in 1895 in Long Island the damage was so noticeable that 

 potatoes suffered a reduction in price of five cents (2Jd.). 



The omnivorous habit of the adult is well known, and although the species has a 

 preference for the Solanaceae, yet it will feed on almost any of the commoner weeds 

 found near the margins of potato fields. The following are some of the food-plants 

 cited by various authors, the list being by no means exhaustive :■ — potato, tomato, 

 eggplant and pepper (0. Lugger J) ; Jamestown weed, nightshade (F. H. Chittenden§) ; 

 radish, turnip, cabbage, raspberry, sunflower and various members of the squash 

 family (C. M. Weed ||) ; beets (A. S. PackardTI). 



An attempt was made during the season to arrive at some idea of the comparative 

 intensity of the flea-beetle injury by making counts of the fenestrations on the leaves 

 of individual shoots. Although a short table has been prepared showing the averages 

 of these results, it is very doubtful if this method of gauging the degree of infestation 

 is very successful, unless one can make daily records. This was impossible, because 

 the spraying and dusting of the potatoes allowed only a short stay at a time at each 

 place. However, the results, such as they are, have been tabulated in the hope that 

 they may be of some use in stimulating others who have the opportunity to attack 

 the problem along this line. 



In one case, at Robbinsville, the Bordeaux mixture seemed to be less efficient 

 than the gypsum and zinc arsenite in warding off the flea-beetle, and it almost 

 appears as if dry poisons, for the time they remain on the leaves, are more effective 

 in their repeUing function than wet poisons. In the long run, however, by reason 

 of their greater powers of adherence, the latter give the better results. At Freehold, 

 on 9th July, the Bordeaux plots had the least injury, and similarly again at Robbins- 

 ville on 13th July, and at Elmer on 16th July. Unsprayed plants, as is to be expected, 

 are more liable to flea-beetle injury, and at Elmer, 22nd August, on the late crop, 

 the average number of holes per leaf was 32 during the second worst attack of the 

 season. The intensity of the infestation at Elmer when the plants were yet young, 

 can be judged by results obtained on 10th June. Here the Bordeaux and lead arsenate 

 combination proved its qualities in keeping the pest at bay. 



The fact that the average number of injuries, as judged from Table VI., were much 

 greater at Elmer on 10th June, is due to the fact that the counts were made on the 

 large radical leaves, which, on account of their having appeared first, suffered 

 greater cumulative damage than the younger leaves on the top shoots, which 

 alone were considered in the later reckonings. 



* Chittenden, F. H.— Bull. No. 19 N. S., U.S. Dept. Agr., 1899, p. 89. 

 t Stewart, F. C— BuU. 113, N.S., N.Y. Agr. Exper. Sta., Geneva, 1896, p. 311. 

 t Lugger, 0.— BuU. 66, Minn. Agr. Exper. Sta., 1890, p. 247. 

 § Chittenden, F. H. — Loc. cit, p. 90. 



II Weed, C. M.— BuU. 29, N.H. CoU. Agr. Exper. Sta., 1893, p. 3. 

 Tj Packard, A. S. — Loc. df., p. 732. 



