sweetly of balsam] The latter is its old English name - very descriptive - very English -
and much more appropriate than 'Native Black Poplar' as the trees are probably not
native anyway, most likely having been introduced by early man in the neolithic, along
with our east Anglian Elms. Nevertheless, Water Poplars are regarded as an endangered
tree throughout Europe, so we must do our bit to save them. Incidentally, the spiral galls
have so far been found on every Water Poplar examined to date, and since it is so highly
specific it can be used to identify a Water Poplar as distinct from the many alien Black
and Balsam Poplars plus their hybrids. This July, for the first time to my knowledge in
Essex, I found the related Pemphigus bursarius on Lombardy Poplar at Becton Sewage
works - these two little aphids must have very sensitive 'hooters' if they can not only
detect a Water Poplar from miles away but do in the presence of the pong from the entire
sewage output of north London!
Mass emergence of Metoecus paradoxus (a beetle parasitic on wasps)
Del Smith 12 Tring Gardens, Harold Hill, Romford, Essex RM3 9EP
delsmith444@btinternet.com
In early July in a house in Cranham (TQ572868), adults of this species started to appear
in a first floor bathroom, they appeared overnight in the room when the window was
often open and the light left on overnight. They appeared in no otherrooms in the house.
I thought it was possible that the beetles were in fact entering the bathroom from the loft
via a gap in a badly fitted light fitting. Mr Gi'een carried out an experiment on the night
of 1-2/8/03. Ensuring no insects were present he closed the windows and door and
turned out the light. The following morning three more Metoecus were found, undoubtedly
from the loft. The loft contains a wasp's nest and I am informed has contained nests on
previous years.
Metoecus is a beetle belonging to the family Rhipiphoridae, it has a very distinctive
appearance in that the wing cases are narrow, taper to a point and do not meet on the
middle line. It is 10-12mm in length. The life history is interesting in that the larvae are
parasitic feeding on social wasp larvae, living within their nests. It is rare amongst beetles
to be truly parasitic. Metoecus larvae are very active when they first hatch, seeking out
wasps, they then attach themselves to the wasp and are carried back to the nest, where
they live inside a larvae, later stages eat wasp larvae from outside in a more typical
predatory fashion.
These insects are widespread in Britain and Europe but are not often seen. They live in
the nests of at least two of our common wasps and were once thought to only live in
underground nests, but there arc now some records of nests in lofts and attics.
Thanks to Graham and Tracy Green for bringing this to my attention and providing a
few specimens.
Essex Field Club Newsletter No. 42, September 2003
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