15
JOINT ESSEX FIELD CLUB/BRITISH PLANT GALL SOCIETY
MEETING HELD ON THE 7th AUGUST 1994
GALLS IN EPPING FOREST......
Eight members of the two organising societies met at the Conservation Centre, High
Beech. Epping Forest had been chosen as the venue partly because of the lack of recent
records from the site, but also in view of the importance work on galls carried out in the
area by Field Club members such as E. J. Lewis and J. Ross in the late 19th and first half
of the 20th centuries respectively However, it is unfortunate that many of the open areas
of the Forest have now been lost leading to a lack of the edge habitats that so often prove
rich in galls.
After a brief introduction by the leaders, the party set off in search of galls, and the car
park proved to be a useful starting point. It is bordered by a good variety of tree and
shrub species, which yielded several of the commoner galls. These included bean galls
induced by the sawfly Pontania proxima on willow, and the gall-mites Eriophyes
macrorhynchus and Aceria pseudoplatani on sycamore. The party then continued in a
north-westerly direction through woods and along roadsides, following a roughly circular
route with the Wake Arms as the furthest point.
Galls on oak, with the exception of Common spangle (caused by the gall-wasp
Neuroterus quercusbaccarum) and Oak marble (Andriscus kollari), were scarce.
However, the thin-walled pea gall caused by the uncommon and localised gall-wasp
Cynips agama was particularly of note. The thicker woodland, dominated by mature
Hornbeam and Beech, had a poor diversity of gall causing species; on Hornbeam, for
example, the party found only galls of the mite Eriophyes tenellus, and other
characteristic arthropod species on this host were apparently absent. However, a few
trees with severe witches brooms caused by the scarce fungus Taphrina carpini were
located, confirming the continued existence here of this species which has long been
known from the Forest.
After a picnic lunch, the Honey Lane Quarters, one of the few remaining open areas of
the Forest, was explored. Here, the galls of the scarce Cynipid Xestophanes brevitarsis
were found on Tormentil. This was one of the most significant finds of the day, as the
species is scarce in Essex and is very much at risk if the loss of open areas continues.
The only other recent county record for this species is at Tiptree Heath, where it is also
under threat by scrub invasion of its habitat.
In all, 48 different galls were recorded, with one or two exceptions these being among the
commoner species found in the county. The enormous pressure on the Forest for
recreational use, together with the lack of traditional management had evidently affected
the diversity of gall-causing species and, regrettably, it is likely that a continued decrease
in the diversity of these organisms will occur.