Mosquito Wrigglers in the trays outside! Little bastards!

I have three trays outside that act as a nursery for seedlings and youngens, and have just noticed wrigglers in the water. So like, short of buying some BT biological shit to kill em, what can I do?

I am currently thinking that a few drops of bleach might keep them .. multiplying, *shrug* but iunno. The plants obviously don't care at all. I'm sure the mozzies would shit nutrients into the water for em, but I don't want the little bastards attacking me all night long.

So, bleech?

no, no bleach. just add a little dribble of oil on to the surface of the water. It will spread out, then the larvae die as they try to leave the trays.

How would I get the oil out the plants afterwards? Would it not grease-up the entire tray(s)?

why is there standing water in them at all? Get rid of the water, problem solved.