I'm coming a bit late to this. Obviously most of the Penlee Green Darner arguments have been rehashed.
One that doesn't seem to have been looked at this time is the damage that is done to genuine conservation by the mixed message that killing a "rarity" gives to the public.
I mentioned the damage that such an incident could do to public opinion, + how acceptance of this incident could be viewed, in post 106 (although perhaps I could have worded it better, and I didn't mention other rare species).
It is important to remember that these are isolated incidents, and that the taking of the SMH has been pretty much condemed by all - including those who have argued that there are valid reasons for killing specimens in some cases.
The value of public opinion to conservation so vastly outweighs the value to science of a voucher specimen as opposed to photographs and a non-fatal clip for DNA, as to render additional debate totally unnecessary.
I agree completely in this case, as I believe do most of those who have posted here (at least where the identity can be confirmed without dissection). The debate about the validity of taking specimens has repeatly referenced the occasional need for this
in groups where identification can not be made from photographs and field notes, rather than claiming that it is always necessary. In my experience this
does not harm public opinion to conservation if done responsibly (with reasons explained if needed).
I also think that the vast majority of twitchers do a far better job of enthusing the public about wildlife than almost anyone except David Attenborough.
I have highlighted the key words used in the above quote in bold. Lets not forget that the collection of the SMH was an isolated incident by a collector taking the specimen solely for his own 'enjoyment' (and yes I believe that I do know this to be true, although I have not, and will not, post reasons on here). I would suggest that
the vast majority of amateur entomologists also do a very good job of enthusing the public about conservation, even though insects are generally seen as less worthy of attention than birds to the general public. Lets not forget about
the minority of twitchers, who rather than enthusing the public actually damage the public view of twitching (and conservation) because of their irresponsible attitude, and frequent disparaging remarks (how many of you have never heard a twitcher deliberately put down someone who has made a beginners mistake in a bird hide - possibly putting them off birdwatching, and conservation, in the process?).
On the subject of DNA, and it's potential to identify which part of Europe these SMH's came from (and potentially the weather patterns they followed), it's an interesting idea, but personally I would have thought that it is a non starter. Due to the migratory nature of the species I would expect that there is relatively little genetic variation across most of Europe (most populations away from the Meditterranean are considered tempory, sometimes being re-established by new immigrants - so DNA is constantly being mixed).
Even if DNA studies could establish the area that the Hadleigh ones came from, it would tell us little more than that because we cannot say for certain
when they arrived (eg. did they arrive in numbers shortly before being discovered this summer, or did a few arrive sometime last year and we are now seeing the result of sucessful breeding?).