224 MAINE AGRICULTURAL EXPERIMENT STATION. 1916. 



DESCRIPTIONS OF LIFE-STAGES AND LIFE-HISTORIES OF MAINE 



SPECIES. 



PIPIZA PISTICOIDES Williston. 



This species is one of the most important if not the 

 most important natural enemy of the Woolly Apple Aphis 

 (Schizoneura lanigera) about Orono. The larvae were plenti- 

 ful among the above-ground colonies of this aphid, especially 

 during August. The eggs are laid by adults, doubtless of a 

 spring generation (developing among one of the elm Schi- 

 zoneura?), as soon as the aerial colonies of the aphis are estab- 

 lished on the apple. 



Good-sized larvae were collected August 3, 16 and September 

 I. Pupae were formed August 14, 21 and 24, the adults emerg- 

 ing from ii to 13 days later. 



So rapacious are these larvae that they practically exterminated 

 the Woolly Apple Aphis about Orono by the first half of Sep- 

 tember. Dr. Edith M. Patch tells me this is the usual experi- 

 ence year after year. 



Walsh and Riley (48, 49, 57) have described and figured a 

 species of this genus, which was found feeding on Schizoneura 

 lanigera and Phylloxera vastatrix, under the name of "The 

 Root-louse Syrphus-fly (Pipiza radicum n. sp.)-" Osten Sacken 

 (38, p. 120) listed this species as a synonym of -femoralis as 

 did also Williston (62, p. 26) with a query. The type specimen 

 appears to be lost but Coquillet (11) concludes from a com- 

 parison of the original description with the type of Pipiza 

 pistica Williston that they are the same, hence the latter a 

 synonym of radicum, and consequently that ''the root-louse 

 Syrphus-fly" should be known as Pipiza radicum Walsh and 

 Riley, being distinct from femoralis Loew. 



Williston (62, p. 29) at the same time that he described 

 Pipiza pistica described another species, P. pisticoides, from a 

 single female from Mount Washington, as follows: 



"Resembles P. pistica very much but seems evidently different. The 

 third joint of the antennae is orbicular, as broad as long; the pile through- 

 out is shorter on the abdomen scarcely discernible; the size is also dis- 

 tinctly smaller." 



Certain specimens collected in Ohio and one specimen, reared 

 from an overwintering puparium among Schizoneura americana 



