178 Turnip Fly. 



Eucoi'la rapae Westw. — Nigra,' nitida ; alis fusco vix tinctis ,* 

 femorum basi et apice, tibiis, tarsisque nisi apice, rufescen- 

 tibus ; abdominis segmento basali pilis albis marginato. 



Longitudo corporis, lin. 1J. Expansio alarum, lin. 3. 

 Habitat in tuberibus gallosis Z?rassicae JXapae. 



The Grove, Hammersmith, Nov. 30. 1834. 



P.S. — The editor has called my attention to a series of 

 communications contained in the fourth volume of the Me- 

 moirs of the Caledonian Horticultural Society (1829), upon the 

 subject of the disease in turnips called anbury, or fingers and 

 toes, forwarded to that Society in answer to a circular issued 

 by the secretary, containing a variety of queries upon the 

 nature and remedies of the disease in question. In one of 

 these memoirs, by Mr. Geo. Sinclair, F.L.S. [now deceased], 

 an account is given of the ravages of a larva found in each of 

 the excrescences of the turnip, and which is stated to produce 

 a species of Cynips. " As soon as the insect is prepared to 

 leave its nidus, the root, or that portion of it formed into 

 galls, begins to putrefy. Several insects are now attracted to 

 the putrefying mass. A species of Musca deposits its eggs on 

 the surface. The larvae burrow in the mass." Whereupon 

 the editor has suggested that it is much more likely that 

 the pupa sent by Mr. Farmer, with his insect from the tur- 

 nip, should be the pupa of the " species of Musca " men- 

 tioned above, than that Mr. Farmer should have mistaken 

 the pupa from the barley for the pupa from the turnip. From 

 what I have above stated, it will be perceived, 1st, That 

 the information received from Mr. Farmer is not sufficiently 

 precise, regard being had to the character of the insects for- 

 warded ; and, secondly, that, in the absence of direct inform- 

 ation, I have been compelled to resort to analogy. Now, if 

 we adopt Mr. Farmer's statement, we have the two following 

 circumstances : — First, that one of the ichneumonidae is 

 herbivorous ; and, secondly, that one of the Cynipidae is para- 

 sitic in the cocoon of a dipterous insect. Hitherto no ichneu- 

 mon has been noticed whose economy is not parasitic; and 

 the Cynipidae (with only two or three recorded exceptions) are 

 herbivorous. But Mr. Sinclair enables us to get over the 

 latter difficulty, by showing that the Cynips and the Musca 

 have no connection with each other, but that both are confined 

 to the turnip. Still, the former remains in all its force : and, 

 knowing that two species of ikfusca attack the barley, I still 

 feel inclined to retain the opinion I have ventured to give 

 above, whereby the difficulty is got over in a more satisfactory 

 manner. — J. O. W. Jan. 1^835. 



