222 MAINE AGRICULTURAL EXPERIMENT STATION. 1916. 



I. Aphidophagous Species. 



Paragus angustifrons Loew. 



Pipiza pisticoides Willist. 



Melanostoma mellinum Linne. 



Sphaerophoria cylindrica Say. 



Sphaerophoria sp. 



Syrphus sp. 



Syrphus americanus Wied. 



Syrphus ribesii Linne. 



Syrphus torvus O. S. 



Syrphus xanthostomus Willist. 



Syrphus nitens Zett. 



Didea fasciata Macq. var. fuscipes Loew. 



II. Short-tailed, Filth-inhabiting Species. 



Tropidia quadrata Say. 

 Syritta pipiens Linne. 



III. Long-tailed, Filth-inhabiting Species. 



Eristalis bastardii Macq. 



Eristalis dimidiata Wied. 



Eristalis arbustorum Linne. 



Eristalis tenax Linne. 



Tubifera lineata Fabr. (Helophilus conostoma Willist.) 



Tubifera trivittata Fabr. (Helophilus latifrons Loew.) 



The Short-tailed and Long-tailed Filth-inhabiting species 

 were, all except the last species, reared from decomposing human 

 faeces at the mouth of a sewer. Tubifera trivittata (Helophilus 

 latifrons} was breeding in old and dried, but recently water- 

 soaked, droppings of cattle, and soft black mould about stumps 

 in an old stumpy pasture where heavy rains had left numerous 

 pools of shallow water. 



The aphidophagous species named above and others not deter- 

 mined were found preying on 33 species of Aphididae and two 

 species of Psyllidae as follows : 



