NATURAL HISTORY, TORONTO REGION
Hormaphis hamamelidis, Fitch, and Hamamelistes spinosus,Shimer, are common on the witch hazel near the city. The former is a conoidal leaf gall, while the latter is a somewhat elliptical spiny structure originated from a flower bud.
Pemphigus vagabundus, Walsh, is a very conspicuous gall at all seasons of the year on cottonwood, Populus deltoides, Marsh. The leaf petioles of the same host are often twisted and enlarged by Pemphigus populicaulis, Fitch.
Colopha ulmicola, Cockscomb-ehn gall, Fitch, is not uncommon. It deforms the leaves of the American elm, Ulmus americana, L.
Four species of Chermes affect the spruces of this region, namely, Chermes abietis, Chol., on Norway spruce (Picea abies, Karst) and Black spruce (Picea mariana, B.S.P.),and Chermes floccus, Patch, Chermes similis, Gill., Chermes pinifoliae, Fitch, on Black spruce.
These galls are produced almost invariably as a spindle-shaped swelling of the stem of the host. They are so conspicuous on account of their size that they often attract attention.
Eucosma scudderiana, Clemens, on the golden-rods, Solidago canadensis, L., and Solidago serotina var. gigantea, Gray (seldom). This gall occurs high up on the stem of the host among the branches. The