Holly Blue in October!

[Chris Raper]

On Thu, 9 Oct 1997 13:52:21 -0400, Andrew Wood
<AndrewGWood at COMPUSERVE.COM> wrote:

>I'm interested in the discussion on Holly Blues (Celastrina argiolus) as
>around me in Hertfordshire this year their numbers have been very low and
>lower in the second than the first brood (on a transect,  well provided
>with holly and ivy, which I walk   4 and 0  (cf 1996 when numbers were24
>and 62.   Last year in Hertfordshire was an excellent year and indeed I saw
>an individual on 19 October 1996, suggesting a third brood.  Yet they were
>common in Cornwall when I was there in July.
>
>I am intrigued by the geographical difference that seems to exist in the
>populations of what I have always thought of as an evenly distributed but
>cyclical species. Can anyone comment on this, or have I just been unlucky?

Hi Andrew,

Don't really know but I was having a similar discussiion with a
reserve manager about Pyramidal Orchids. On a couple of reserves he
manages they were very poor this year but I maintain that on the ite I
manage they had a much better year than last year! :-\

As for Leps (trying to drag it back onto subject :-)) - the sunny, dry
and cold Spring followed by cool, wet weather caused a massive crash
in the numbers of Spring moths and butterflies - but prolonged their
flight period! Later in the year I noticed that double-brooded species
that had been affected by the Spring weather showed a marked reduction
in numbers. They were around but in much lower numbers.

Now in almost all those cases other people were reporting slightly
different effects. The only conclusion we could come to was that a)
you couldn't base any meaningful management decision on the numbers
for 1997 (because weather was such a massive influence) and b)
different vegetation cover and aspect could give dramatically
different populations of the same thing - presumably due to them
sheltering or exposing the Leps to the weather.

Cheers
Chris R.