OF EPPING FOREST.
151
Genus ANDRICUS (Hartig).
So far as we know at present, the genus Andricus includes a
greater number of oak gall-making species than any other of our
genera. I have kept the generic named Andricus for both gener-
ations. Adler gives Aphilotrix as the generic name of the
agamic generation. Some species have no sexual generation
(A. seminationis (Gir.), A. quadrilineatus (Htg), etc.); these have
only one generation a year.
The agamic forms of this genus have the antennae as
a rule 14-jointed, 13 antennae joints being the exception. The
colour varies, a few species being quite black.
The sexual forms differ from the agamic in having the
antennae as a rule 13-jointed. Andricus curvator (Htg), however,
has 14-jointed antennae. The colour is not so variable, the
majority of species being quite black.
I have found that in some cases the agamic forms of this
genus are apparently much more common than the corres-
ponding sexual generation. This is especially the case with such
species as A. callidoma (Htg.) and A. fecundatrix (Htg.) A.
callidoma is fairly common in Epping Forest, but I have only once
found A. cirratus (Adler). A. fecundatrix again is exceedingly
common, but I have not been able to find a single specimen of
A. pilosus (Adler), in spite of repeated search. I have also
obtained several specimens of A. malpighii (Adler), but have
not met with A. nudus. This might be due to the fact
that these catkin galls are easily passed over unnoticed;
but I do not think that this is entirely the reason, as I thoroughly
examined the catkins on a great number of trees without success.
During two days' collecting in the neighbourhood of Lynton,
North Devon, I found all three species to be very common at
the beginning of June, 1900.
(11.) Agamic Generation I. Andricus sieboldii (Htg.)
Inquiline. Synergus incrassatus (Htg.)
Gall.
Appear through the bark of the stems of the oak, usually
near the base not far from the ground. They are found as a rule
on small oaks in hedges, and on old pollard oaks. The galls
penetrate deeply into the wood, stunting the growth, and some-
times killing the younger plants. Colour, Cherry red when young,