How about stuffing the books in a freezer? Apparently this can kill both bugs and their eggs, although I'm not sure it works on the particular kind of bugs in these books:
Also there exist "ultra low" freezers which can bring temperature waay lower than the regular -20 Celsius. Like -80 or something. I doubt any bug or egg can survive such environment, although the books should suffer no harm.
I do not doubt that freezing them would kill the bugs. I would be worried that unless it is very carefully managed it might damage the books though. In particular i would worry that moisture from the air would freeze on the books and as they are thawed they would get water damaged. Or that moisture trapped inside the bindings would form ice crystals and physically damage the books as they form.
None of these are concern with the hypoxic treatment they choose. Plus the nitrogen atmosphere treatment is so much simpler on the practical level. Instead of bringing in freezers and powering them for the whole duration of the treatment all you need is some crates, plastic bags and nitrogen bottles. Makes it much easier to bring the treatment where the books are, thus you avoid all kind of complications with transporting the books.
Well, it's an idea. Perhaps de-humidifying the books first...
The hypoxic approach needs to last at least until eggs hatch, otherwise you're back to square one. And I'm not so sure if a plastic bag can hold tight for long without leaking (nitrogen out, air in).
One potential problem might be that they have to treat the entire collection of 400,000 books at the same time (which makes sense because otherwise you risk rotating the beetles through the collection). So they'd have to find such an ultra-low temp freezer that was large enough to hold 400k books.
Also, although I assume this is a very rare ability among insects and probably not applicable to the "drugstore beetle" from this article, check out this insane fly species I found while looking for freeze tolerant insects: https://en.wikipedia.org/wiki/Polypedilum_vanderplanki
It (or its larvae, anyway) can survive temperatures as low as 3K!
> One potential problem might be that they have to treat the entire collection of 400,000 books at the same time (which makes sense because otherwise you risk rotating the beetles through the collection). So they'd have to find such an ultra-low temp freezer that was large enough to hold 400k books.
They don't have to treat them all in the same place. They could use more than one freezer.
Or you put them in a sealed environment with no oxygen, killing every single one of these beetles.
I'm not sure that the more lethal option is "tame".