124 The Galls of Essex; a Contribution to a
Spiraea Ulmaria, L. Leaf. Wart-
like swellings on the surface of the
leaf projecting both on the upper
side and under side, mostly red-
dish above and white or pale green
below. Many on one leaf, but only
one larva in each gall, within
which it pupates. Cecidomyia Ul-
mariae, Bremi. (Fig. 4).
Rubus fruticosus, L. Stem. A
considerable thickening of the stem
for an inch or more in length,
which is at first green and later
becomes brown. The gall is multi-
locular, and is often very con-
spicuous in winter, showing the
holes from which the gall-flies
have emerged. Diastrophus Rubi,
Hartig. (Fig. 5).
Rubus caesius, L. Stem. Galls
of D. Rubi, as on R. fruticosus.
Rubus caesius, L. Stem. A

Fig. 4. Cecidomyia Ulmariae.
thickening of the stem, but gene-

Fig. 5. Diastrophus Rubi.
rally more regularly rounded or
oval than in the gall of D. Rubi; also mostly much smaller,
and does not interfere with the direct growth of the stem,
as is often the case with that species. The gall is multi-
locular, and the larvae pupate in a snow-white pupa case
within it. Lasioptera Rubi, De Geer.
Rubus fruticosus, L. Leaf. Thickened and folded leaf
longitudinally along the superior veins. The pale yellow
larvae leave the pseudo-gall and pupate in the earth. Ceci-
domyia plicatrix, H. Loew.
Potentilla reptans, L. Stem and leaf-stalk. Hard,
brown, very irregularly shaped, though generally round or
oval, swellings of the stem or leaf-stalk; these galls are
usually multilocular, and occur singly or more frequently
many together on a stem. The gall-flies emerge from the