I am not Lynne Truss, but someone should sort this out

I am being driven crazy by apostrophes at the moment.  Not all apostrophes, just these ones:

Same book.  Same title.  Different apostrophe placement.  Why?? WHY?? WHY??????

Initially I was under the impression that these were the paperback and hardback covers, which would have been even weirder, but as it turns out they're the UK (on the left) and the US (on the right) versions.  Different publishers. Same question though - why the difference in where the apostrophes appear?  How many hornets are there supposed to be?

I am not the only one to have noticed .  No one seems to have any answers though, which is what is driving me crazy.   It's not as if hornets are like fish and sheep - one fish, many fish, one sheep, many sheep, one hornet, many hornet.....nope.  It just doesn't sound right. 

So the apostrophe placement is technically correct in both cases, but definitely changes the meaning.  Which raises more questions.  Which one is correct?  And was the other one just a (monumental) mistake?  I doubt it.  More likely, there were many meetings about the apostrophe. I am imagining lengthy discussions about numbers of hornets, their capacity for loneliness and how many of them it takes to build a nest.  Perhaps the American hornets are just super-efficient.  (The Green Hornet - he was American, wasn't he?  I forget what his super-powers were, but I bet he was pretty good at building things.)

 I haven't read enough of the book to find out the significance of the title, but I've read the first two books and know enough about Salander, aka 'The Girl Who', to guess that in this installment she's probably up to a bit more than just irritating some flying stinging creatures. Or creature.  I don't think she'll find herself fighting against the Green Hornet, either, so my money is on the nest being a metaphorical, not a literal one.  Maybe the number of hornets isn't all that important.

Then again, I've just remembered, ages ago someone told me something slightly spoiler-ish about the title which, if it's true, suggests otherwise (sort of).  I don't know. Maybe I should just finish reading the book and find out. 

This all reminds me of my favourite misplaced  apostrophe, which I saw in a newsagent's window in Clapham, on a poster advertising a room for rent.  After the price per week, it said Bill's included.  To this day, I wonder whether Bill ever knew he was part of the deal.