Due to the wording and style, I've always thought this poster to be American in origin.
I have both the above leaflets: mine is undated and I think this may be the 'original' version issued in late 1941 when butterflies were first used against the UK. My hunch is that they were reissued with the /43 issue date. I've always been suspect about the yellow butterfly leaflets with the blue writing. There is a guy on ebay who has a permanent, never-ending constant supply of them for sale. The feel and colour of the paper, together with the blue print, seems very odd for wartime, especially when you compare it with other wartime leaflets of the period. The jury is still out on that one...
I was very lucky to pick up the British full colour 30" x 20" 'Beware of the Butterfly Bomb' poster some years ago, surely up there with the Firebomb Fritz poster. The dealer had glazed and framed it and assured me that he would send it padded wrapped in the post. The idiot put some polystyrene popcorn in with the parcel and of course they all sunk to the bottom, leaving the glass completely exposed in the box: hey presto, the frame and glass was smashed to bits on arrival - fortunately the poster was undamaged!
I also have the full set of ARP instructional glass slides of the Butterfly Bomb: the dealer said they showed "various types of wild butterflies around Britain" - he was sort of right!