On leaf, beneath, stoutly conical, varying in size from 1½ mm. to 4 mm. high. Tip erect or often bent to one side. Smooth, green to purplish-red and finally a brown when old. Attached to smaller veins by short pedicel, hidden from view, however, by the rounded base of the gall. Walls medium in thickness, possessing the rather soft texture of charcoal when dry; brown in color.
This form is often found in enormous numbers on certain trees, bringing about early disintegration of the affected leaves. The lower leaves are more heavily infested due to the fact that the insects are apt to reach these first in their flight from the ground in the spring.
- Osten Sacken, Lowe’s Monogr. Dip. N. Am. Pt. 1, p. 192. 1862.
- Beutenmuller, Am. Mus. Nat. Hist. Guide Leaflet No. 16, p. 28, Fig. 59.
- Reprint from Am. Mus. Jour. Vol. 4, 1904.
14. Cecidomyia sp. Cecidium nov.
Leaf, under side, distal half conic-attenuate from the bulbous or sub-globular proximal half. Covered with long, coarse trichomes, the longest being half the length of the gall. Trichomes brown. Tip of gall generally darker than rest. 3-4 mm. high, 2-3 mm. wide. Cavity sub-spherical somewhat depressed at right angles to axis of gall. Walls relatively thick, especially the proximal part. Apical canal evident in median longitudinal section. Gall attached by short and broad pillar of tissue extending from the leaf into the fleshy base.
Gypsum, Ohio, August, on H. ovata.
Type specimens at Ohio State University.
15. Cecidomyia sp. Cecidium nov.
On leaf, under side, small, conic galls, generally found in pairs closely appressed to each other but not confluent. Distal attenuate ⅓ rather sharply constricted from the sub-globular ⅔ of the gall and generally turned to one side. 2 mm. high, 1½-2 mm. broad at base. Yellowish in color, definitely and constantly pubescent. Interiorly the lining of the sub-globular larval chamber is deep blue-black in color. Walls of medium thickness. Comparatively large region of the base involved in the attachment of the gall.
Collected in Hocking County, Ohio, on H. alba, July.