76 THE REPORT OF THE No. 19 



Family-Tryyetidoe. 



This family comprises a large number of rather small flies, usually 

 with prettily-marked wing's. A few species belonging to the genus Trypeta 

 produce galls on the stems of composites. 



Hymenoptera. 

 Family-7'enihTedinidcc. 



Of this family the Nematinse produce galls. The head and thorax are 

 wide. The base of the abdomen is broadly joined to the thorax and the 

 abdomen of the female is furnished with a pair of claws. The larvae have 

 from twelve to sixteen prolegs. These insects have been very thoroughly 

 taken up by Norton in his monograph on the Nematinse. A large number 

 make galls on Willow. 



Family-CynipidcB. Gall Flies. 



This is a family of very minute, four winged insects. In the adult gall- 

 fly the abdomen is unusually compressed and joined to the thorax by a short 

 peduncle., the first abdominal segment. The ovipositor is long and slender. 

 The insect deposits its eggs within the tissues of the plant by piercing it 

 with its ovipositor. The galls produced are closed and the insect emerges at 

 maturity through a hole it cuts in the gall. 



The writer's thanks should be here expressed to those who have so kindly 

 assisted in the preparation of this paper. I am under special obligation to 

 Prof. Bethune, O.A.C., Guelph ; Dr. E. Porter Felt, State Entomologist, 

 N.Y. ; Mr. A. Cosens, Toronto, and Mr. W. E. Thompson, Guelph, and 

 Mr. CD. Jarvis, Storrs, Conn. 



The present list is arranged alphabetically by host plants. 

 Affecting Alder. 



A white, frost-like erineum on under side of leaf in the axils of the veins. 

 Trichomes dense, pellucid. — Eriophyes sp. — Alnus incana. 



A small, red or green pubescent pocket gall on leaf. Alder Pocket Gall — 

 Eriophyes sp. — Alnus incana. 



A rounded gall, a deformation of the terminal bud. Alder Bud Gall. — 

 Dasyneura serrulatoe — O.S. Alnus incana. 



Affecting Ash. 



Spherical, pulpy green galls about the size of a pea, springing from the 

 upper surface of the midribs or veins. Ash Ball Gall — Cecidomyiadoe — 

 Fraxinus sambucifolia. 



Elongated, green, succulent galls on the under side of the leaf. Ash 

 Midrib Gall — Cecidomyia pellex — O.S. Plate F., fig. 5. Fraxinus ameri- 

 cana. 



Small, irregular, smooth, more or less spherical capsule gall, protruding 

 on both sides of the leaf. Ash Mite Gall — Eriophyes fraxini — Garman, Fraxi- 

 nus americana. 



Pinkish white, elongated capsule galls on the veins of the leaf. Yen- 

 trally the galls appear as white, hairy projections following the veins. Ash 

 Vein Gall — Eriophyes sp. 



