December, '21] johannsen: seed potato maggot 503 



vines were all spotted and the insects were most abundant. It seems 

 probable that there are two and three broods in the latitude of Massachu- 

 setts. 



Control of the species is rendered difificult in cases where the vines 

 are climbing on the walls of buildings, since the njinphs are nearly all 

 on the underside of the leaves and difficult to reach with a spray. Where 

 the underside of the leaves can be reached, as on open porches and sum- 

 mer houses sprays of soap or nicotine solutions may be used and the writer 

 has obtained effective control from a strong spray of water applied 

 under considerable pressure and at intervals, directed towards the 

 under surfaces of the leaves. 



A SEED POTATO MAGGOT {HYLEMYIA TRICHODACTYLA 



RONDANI) 



By O. A. JoHAXXSEN, Ithaca, N. Y. 



On June 27, 1910, I bred male specimens of an Anthomyiid fly, 

 Hylemyia (Phorbia) trichodaciyla Rondani from maggots infesting a 

 lot of seed potatoes which had been fonvarded to the Maine Agricultural 

 Experiment Station from Aroostook Co., Maine, by a farmer who said 

 his potatoes were severely infested. 



Concerning the habits of this species but little has been published, 

 though the adult fly is not uncommon. In the Cornell University 

 Collection are specimens from Aroostook Co., Maine, Peru, N. Y., 

 Ithaca, N. Y., Sandford, Ontario, and Truro, Nova Scotia; the 

 collection dates ranging from May to July. Dr. 0. Oberstein (Zeit- 

 schrift f. Pflanzenkrank. 24:385, 1914) records this species as injuring 

 young cucum.ber plants in Lower Silesia where a one-half acre field 

 under observ^ation showed 80% injur>^ The maggots mined in the 

 stems of the young plants causing them to die in a few days. When 

 full grown the lar\'ae descended into the soil where they pupated. The 

 specimens which I had under observation remained in the pupal stage 

 about one week. 



As the fly has a wide distribution and is fairly common, it is not 

 unlikely that it is of economic importance in the United States also, 

 but by reason of its great similarity to the seed-corn fly {Hylemyia 

 cilicrura Rondani =H. Jusciceps Slingerland not Zetterstedt), it may 

 have been m.istaken at times for this species. The males of these two 

 forms resemble each other in having the hind tibia ciliated on the inner 

 (flexor) side (See SHngcrland, Bulletin 78, Cornell Agricultural Experi- 

 ment Station page 495), but differ in that H. trichodactyla has a few 



