Diplosis punicei

Cecidomyiid galls are found on leaves and stems of herbaceous plants, on leaves and twigs of shrubs, and trees, and deformed buds and flowers. The Cecidomyiid galls are morphologically as destructive as the producers; this may be said of galls generally, so that a description of the gall may be even more specific than a description of the producer as expressive of the biological relations between the "animal and the plant."

From 1887 to 1902 I found these galls common on Aster puniceus, one of our fine vigorous flowers which is very common, growing in wet ravines everywhere around Toronto. From 1890 to 1898 I made annual collections of galls in the spring and in the fall. The galls are on branches of the flowering panicle; they are spindle-form swellings of the branches, and in size range from 5x10 mm., diameter of stem below gall 2.5 to 5 x 15 mm. The galls are one-celled, the larvae of a pale straw colour; the producers are of the Diplosis type, and very similar to the producers of a similar gall on branches of flowering panicle of Aster diplopappus. The following is one of the nine annual entries in my note book: "April 9, 1893, collected in Greenwood and Casci ravines, East of Toronto, a lot of over 50 galls from flowering branches of Aster puniceus. Galls spindle-form, 5 x15 mm, diameter below gall 3 mm; another smaller lot measured 4x8 mm., diameter of branch below gall 2.5, mm. From May 30 to June 5, 1893, Diplosis producers emerged. From June 1 to June 11, 1893, two species of parasites emerged.

"June 11, 1893, specimens of gall producers and parasites mailed to Dr. Riley.

"July 29, 1893, note from Dr. Riley: ' Unknown to me.' "

I have found this gall common in Whitchurch, Owen Sound, Fitzwilliam Island, North Bruce, Grimsby, and no doubt they ate more or less common wherever this stately host Aster is found.