len writes:
not much help out there hey john,
especially for the purchase of the product(s), Bacillus thuringiensis
israelensis (Bti). would think this is what the local gov' uses? they
may be able to tell you how or where to buy it?

here is another product suggested:

methoprene

Yes, those are the two I was chasing up.

how would using vege' oil go? it may not evaporate like kero' all that
is needed is th stop their access to oxygen, that's all the kero'
does.

That's a thought, but oil that is never going to evaporate may
cause problems when it comes to tiling, etc. I expect it would
soak into the concrete walls and floor. They do pump as much water
as they can out of the pool from time to time, but wrigglers only
need the remaining few mm to survive in. Then there is all the
water pooled in the churned-up yard, too.

I think the BTI would be the best, if it works as described in the
literature.

Thing is, we're not Robinson Caruso here. There must be hundreds of
people facing the same problem at this very minute. I'd be surprised
to learn there is no local availability of the above commercial
products.

Thanks for your suggestions.
--
John Savage (my news address is not valid for email)