OF EPPING FOREST.
173
The Cynips kollari galls as a rule mature in September, the
flies emerging in October, Sometimes they emerge early in
September, while some remain in the galls during the winter,
appearing in April or May.
The eggs are laid in the buds.
According to Beyerinck, who carried on experiments with this
fly in 1881, the first sign of gall formation occurs at the end of
May, maturity being reached in September, and oviposition
taking place in October. According to my own observations,
the galls are still very small at the beginning of July, dark
reddish brown in colour with a prominent red apex; by the
second week in July they had assumed a more globular appear-
ance and changed their purple colour for green, becoming golden
yellow before turning brown at the end of August. When
quite young I found in many instances that there were two galls
growing out from the axil of the leaf, one being of larger size
than the other as a rule, in which case the smaller dried up. In
other cases both galls continued to grow together. The
prominent apex of the young gall is represented on the mature
gall by a small point.
When parasitised the galls are often smaller and much darker
in colour than the non-parasitised galls. The difference is some-
times very noticeable. In such cases, on making a section
through one of these galls it will often be noticed that towards
the centre there is a circle consisting of five or six cells of
Synergid larvae which have exterminated the cell of the original
maker of the gail together with its occupant.
Over Europe the gall is widely distributed, but it is not
found very far north. It has been known in Britain for about
seventy years, and was probably introduced about 1830. It first
made its appearance in Devonshire, whence it has spread over
England and Scotland. I have found it abundant this year in
different parts of Kent, Devon, Monmouth, Brecon, and Cheshire.
In Epping Forest it is very common, but I have not found it
so abundant as in many other localities. First appearance noted,
June 30th.
In conclusion, I may add that my researches have extended
over a small portion of Epping Forest only, namely, that part