No. 6. DEPARTMENT OF AGRICULTURE. 589 



fertilization. When full grown the maggots escape from the blos- 

 som buds and drop to the ground and enter the soil, where they re- 

 main until the following spring when the gnats emerge and deposit 

 eggs in the blossom buds. 



When a large number of the blossom buds in a cluster are in- 

 fested the result is a very ragged cluster of fruit. Where the in- 

 festation is moderate, or light, sufficient berries persist to mature a 

 well-developed cluster, as yet no effective means of control have 

 been devised for this pest. During the past live years its injurious 

 effect upon the grape crop of Erie county has not been marked. 

 Yet it is so thoroughly disseminated through the vineyards that 

 should conditions favor a great increase in numbers it may readily 

 develop into a very serious pest. 



The ''Kose Chafer" Maciodactylus subspinosus is quite injurious 

 in limited areas of vineyard on sandy soils along the lake shore 

 of the township of North East, Pa. This insect is especially injuri- 

 ous to the Concord grape crop since in attacking this variety the 

 insect does more of its feeding upon the blossom clusters and small 

 berries than upon the foliage. Hence, even a moderate number of 

 beetles infesting a vine may do a gieat amount of injury in a short 

 time. Observations indicate that by far the greater part of the in- 

 jury done just before and during the blossoming period of the 

 grape vine. Ordinarily the beetles are present on the vines for only 

 a short period. This makes it necessary for the grape grower whose 

 vineyard is subject to attack by this pest to have his equipment in 

 readiness as soon as the first rose-chafers appear upon the vines, foi> 

 it frequently happens that they will swarm into a vineyard in large 

 number in the course of a few hours. 



In the course of our investigations upon this pest spraying ex- 

 periments have been conducted for the past four seasons using five 

 pounds of arsenate of lead to 50 gallons of water or Bordeaux mix- 

 ture. In several of these experiments the results have been quite 

 satisfactory. Observations indicate that arsenical poison ap])lica-. 

 tions to be effective against this pest must be verj- thorough and 

 should be axjplied just before the beetles appear upon the vines ir 

 large numbers. 



If the beetles are very numerous it is sometimes necessary to 

 make repeated applications every dav or two uiilil the beetles dis- 

 appear. In our spraying experiments of the past sen son a very 

 marked decrease in the number of beetles was observed on vines 

 sprayed June 5th and Tth. A count made on 50 vines on the sprayed 

 plat showed 96 beetles as against 865 beetles on 50 vines in acljacent 

 nnsprayed plat. The result in crop yield in this experiment showed 

 an increase of half a ton of grapes per acre on the sprayed plat. 



Since it is desirable and necessary to spray most vineyards at 

 the time of appearance of the rose-chafer beetles for other insect 

 and fungus troubles there is no doubt that it is more economical 

 and effective to resort to the spray method of control than to hand- 

 pick the beetles. Although on limited areas aird whe'e spray ap- 

 jjaratus is not available the latter method will greatly reduce the de- 

 tructiveness of this pest. 



The Grape-Leaf-Eopper. Tijphlocijha comrs. is another grape in- 

 sect pest that has greatly increased in numbers and destructive- 

 ness in Erie county during the past three or four years. It is now 



