Subject: White-letter irstteak [Strymonidia w-album]

From: [email-masked]
Date: Sat, 12 Aug 95 08:44:10 -0500

1995 has again been a good year for the White-letter Hairstreak
[Strymonidia w-album (aka Satyrium w-album)] in the UK.  Dutch elm
disease ["DED"] killed off most elm trees about 20 years ago.  Here
in NW Surrey, in the outer suburbs of SW London, young elm trees
(mainly Ulmus procera) have been reaching maturity.  The White-
letter Hairstreak has been widely recorded during the past few
years as they clearly prefer mature trees.
 
Unfortunately, about 1 in 6 trees have been killed by DED both
this year and last and there are now fewer Hairstreak colonies.
It would appear that within a few years numbers of both mature
trees and the butterfly will again fall to a low level.
 
I am aware of attempts to use DED-resistant trees (e.g. Sapporo
Autumn Gold - U japonica x pumila) has been moderately useful
for maintaining colonies of various insects.  Also, Brighton (a
south coast town surrounded by hills) has been able to keep a
number of old elms by rigorous tree-surgery efforts wherever they
see DED.  With DED a "global" problem, does anyone know of other
ways of maintaining an elm environment?  Elms trimmed to form
hedges seem to be DED-resistant, so does pollarding work?
 
Bill Gerrard
[email-masked]