Diastrophus fragariae, n. sp.

Gall — On the petiole of Strawberry: Polythalamous, elongate cylindrical swelling tapering at each end. Red and villose like the rest of the petiole. The internal structure is spongy and contains a single row of 5-20 larval chambers. Length from about 25 to 50 mm. Width 3-5 mm.

Habitat — Toronto, Canada (A. Cosens).

The gall of this species has long been known. Saunders mentions it in his "Insects Injurious to Fruits," 1887, p. 331, and calls it the Strawberry Leaf-Stem Gall. Prof. S. A. Forbes also mentions the gall in the 22nd Report of the State Entomologist of Illinois, 1883 (1884), p. 97. H. F. Bassett speaks of a Cynipidous gall occasionally seen on the petiole of strawberry leaves (Trans. Am. Ent. Soc, Vol. XXVI, 1900, p. 325). Mr. L. H. Weld found the galls at Ithaca, New York and Evanston, Illinois and I found the same in the vicinity of New York City for some years past. In August, 1913, Mr. A. Cosens collected the gall on wild strawberry in Toronto, Canada. He transplanted some of the infested plants into pots and managed to mature the galls from which he reared five males, being the first one to succeed in obtaining the flies.

The illustration is from a sketch made by Mr. Weld and re- drawn by Mrs. E. L. Beutenmuller.

Diastrophus fragariae Beutenmüller, 1915

Feeds on: Induces galls on Fragaria virginiana Duch.

Distribution: United States: Michigan, Minnesota; Canada: Ontario

Diastrophus smilacis

Strawberry petiole gall. A cylindrical gall on the petiole of a leaf, 20-60 mm. long by about 5 mm. in diameter, containing 8-20 cells, red in summer, turning brown later. Flies emerged June 2, 1918.

Diastrophus fragariae

Fragaria virginiana

Cylindrical enlargement of the petiole 25-30 mm long by 3-5 mm in dia, containing a single row of 5-20 cells. Found on wild and cultivated varieties.

[Photo caption]
A fusiform enlargement of the petiole.

On wild and cultivated strawberry. See Fig 320 above. For rearing dig up the plant when the gall is seen in June and transplant to pots or where it can be found in the fall. Adults emerged the next spring June 2 (Chi). Brodie reared the maker May 18-25 at Toronto.

Diastrophus fragariae
Strawberry leaf petiole gall wasp

Host: Virginia strawberry (Fragaria virginiana).

Gall location: On the leaf petiole.

Description: Multiple-chambered swellings, usually cylindrical. Often with a segmented appearance due to the positioning of chambers in a distinct row within the gall tissue. Sometimes with fine hairs. 2-6 centimeters in length and less than a centimeter in diameter. Green to red when fresh to brown when dried and old.

Range: This gall likely occurs throughout the range of the Virginia strawberry, but thus far is known from the Northeast and Upper Midwest, and is especially well-sighted in New England.

This gall has been found in both natural and cultivated systems. Mature galls may be difficult to locate in the field as the stems and leaves of the host plant are prone to withering. However, plants bearing fresh galls may be transplanted and cared for so as to allow the gall to mature.