The former M, Sir Miles Messervy, is a keen amateur lepidopterist. This we learn in “On her Majesty’s Secret Service” (OHMSS) when Bond visits him in his home.
Bond watches M who handles a butterfly in his collection and Bond says:
“Unusually small for a Nymphalis polychloris.”
The butterfly Nymphalis polychloros (Latin name given by Swedish botanist/zoologist Carl Linnaeus in 1758)
is better known as “Large Tortoiseshell” and sometimes as the “Blackleg Tortoiseshell“.
It is of the Nymphalidae family and is found throughout Europe, northern Africa and western Asia.
Since the 1970’s however the Large Tortoiseshell is extremely rare in Britain which curiuosly ties in with the 1969 realease of OHMSS.
In the 1990’s it was considered to be extinct or near extinct in the UK.
M seems to have a rare specimen in his cabinet.
As for the pupation, well according to the site LearnaboutButterflies.com:
“The larvae are black, covered with sharp orange spikes and peppered with tiny white dots, giving them a greyish appearance. They live communally in conspicuous silk webs spun on the twigs of the foodplants. If they are disturbed by a bird the whole group jerks in unison. As they grow older they split into smaller groups, and become solitary just prior to pupation.
When fully grown in early June, the larvae descend from the treetops, and wander a short distance to pupate. The pupa is brown, marked with gold spots, slightly spiky in appearance, and resembles a withered dead leaf. It is formed hanging by the cremaster from twigs or branches on the lower part of various bushes and trees.”
Bond is rather lucky to point out the exact species of butterflies.
The Large Tortoiseshell is apparently (and logically) similar to the Small Tortoiseshell (Nymphalis urticae).
But Bond does not remark: “Fine Nymphalis urticae you’ve got there, bosso.”
No, that would’ve been to easy. As well as M replies, not without some irritation:
“I wasn’t aware that your expertise included lepidoptery.”
International names for Nymphalis Polychloris
Swedish: Körsbärsfuks
Spanish: Olmera
French: La Grand tortue
German: Grosser Fuchs
Polish: Rusalka wierzbowiec
Danish: Kirsebaertakvinge
007 Under the Mango Tree 
Terk Estenfuge
December 24, 2013
The exchange regarding the butterfly is one of the most absurd in all the Bond films.
That Bond would accurately identify that insect is beyond belief; this despite the fact that we know he was highly educated (he learned Japanese at Cambridge, and has earned the title of Commander).
There were better script options available.
BOND: “Playing with your bugs again, M.?”
M: “I’ll have you know, double-o-seven, that this is a Nymphalis polychloris.”
BOND: “Looks like a bug to me… Sir.”
or…
BOND: “That’s one ugly moth, M. Sure you want to keep it?
M: “I’ll have you know, double-o-seven, that this is a rare Nymphalis polychloris. Possibly the last one in Britain.”
BOND: “Probably shouldn’t have killed it then.”
or…
BOND: “Pulling the wings off flies again, Sir?”
M: “I’ll have you know that lepidoptery is serious science. This is a Nymphalis polychloris.”
BOND: “I knew a girl who was a nyph…”
M: “What exactly do you want, double-o-seven?”
or…
BOND: “Rather small for a hecalesia formosus.”
M: “I’ll have you know, double-o-seven, that this is a Nymphalis polychloris, and that it is of average size.”
BOND: “Oh, I see…”
M: “You can’t possibly see, double-o-seven. Every time you visit me at home you antagonize me with that ‘hecalesia formosus’ line. Are you doing it on purpose?”
BOND: “No, Sir, it’s just that…”
M: “Yes, double-o-seven?”
BOND: “… they all look the same to me.”
M: (fuming) “Will you please tell me why I keep you around?”
BOND: (musing) “Probably for the same reason you collect butterflies.”
M: “I took up lepidoptery to calm my nerves after having to deal with you at the office. It is supposed to be a relaxing hobby.”
BOND: “It doesn’t seem to be working. Perhaps you could take up bullfighting?”