FIELD PHENOMENA DUE TO MICROSCOPIC ORGANISMS. 5
cocoons. He therefore found that the scarcity of males of Methoca
is due at least in part to the fact that the female is capable of
parthenogenetic reproduction. He has just informed me that
from the five cocoons he obtained five males this summer. This
opens up a very interesting theme for speculation, but till more
evidence is forthcoming I would prefer to postpone discussion
of the meaning of the phenomenon disclosed.
Methoca has been recorded from Southend, and also from the
Colchester district, so we can claim it as an Essex insect. It has
also been taken at Hampstead Heath and at Oxshott and other
places in Surrey, as well as a number of other localities in England.
It is likely that it would be found in any sandy locality frequented
by Tiger-beetles in Epping Forest and elsewhere.
DESCRIPTION OF PLATE I.
METHOCA ICHNEUMONIDES LATR.
Fig. 1.—Female after depositing second egg. Aug. 29.
Fig. 2.—Second egg on ventral surface of abdomen of Cicindela
campestris. Aug. 29.
Fig. 3.—Larva from second egg, feeding. Sept. 11, (3 days old.
Fig. 4.—Same larva. Sept. 13, 8 days old.
Fig. 5.—Larva from first egg, nearly full fed. Sept. 20, 23 days after
egg deposited.
Fig. 6.—Same larva beginning to spin its cocoon. Sept. 21.
Fig. 7.—Completed cocoon. Sept. 23.
SOME FIELD PHENOMENA DUE DIRECTLY
TO MICROSCOPIC ORGANISMS.
(Being a Presidential Address delivered to the Club on 26th March,
1927.)
By D. J. SCOURFIELD, I.S.O., F.L.S., F.Z.S., F.R.M.S.
WHEN I first commenced to consider the question of a
subject for an address to you to-day. I must confess that I
was in some difficulty, because it seemed rather hopeless for one.
whose scientific work had been mainly concerned with micro-
scopic organisms to be able to speak on any of the topics with
which a Field Club is generally supposed to deal. A chance
discovery of a patch of "Red Snow" during a holiday last
summer among the Alps of Savoy led me, however, to turn over