136 THIRTIETH REPORT ON THE STATE MUSEUM. [24] 



m. ISOSOMA VITIS SAUHDERS. 



THE GRAPE-SEED FLY. 



During the early part of September of the present year 

 (1876), a cluster of grapes, in very bad condition, which had 

 been received at the office of the Country Gentleman, of 

 Albany, was submitted to my examination, with a request for 

 information as to the cause of the injury or disease. It was 

 accompanied with the following letter from the gentleman in 

 whose garden, at Plainfield, N. J., the grapes had grown : 



EDS. COUNTRY GENTLEMAN. I send you by mail to-day a 

 single bunch of Walter grape, to ask if you will tell me in the 

 columns of your paper, what is the matter with my grapes. 

 They have been affected in same manner since the first year 

 they bore (now the third year of bearing), but never so badly 

 as this year. The disease attacks all kinds (I have about a 

 dozen), and in different parts of my garden. It shows itself 

 about the time of ripening, and this year promises to destroy 

 the whole crop before they are fairly ready to pick. If this 

 bunch carries well, you will probably notice a berry or two 

 just touched, and you will see that the puncture is very small. 

 Dr. Hexamer thinks it may be sun-burn, but I am sure this is 

 not the trouble, for this very bunch which I send you was cut 

 from underneath heavy foliage, and bunches heavily shaded 

 are just as badly affected as others more exposed. I have 

 watched for bees and wasps, but find scarcely any. Occa- 

 sionally a single bee will be found sucking the juice of a berry 

 already broken. Neither do I see many birds on the vines, 

 though we have English sparrows in the neighborhood. 

 The vines are very thrifty, and are taken as good care of as I 

 know how to do. 



H. E. M. 



The nature of the difficulty was so singularly concealed that 

 it was not readily detected by me. A critical examination, 

 however, brought to view the hidden cause, and enabled me 

 to return the following answer : 



The injury which threatens to destroy an entire crop of 

 grapes, as above narrated, proceeds from an insect pest which 

 promises to prove very detrimental to the grape-growing 



