Water boatmen generally are not predatory. They mostly feed on plants and
algae. Great diving beetles are predatory but depending upon their size,
mosquito larvae may be too small to interest them - they would look for
tadpoles, small fish etc.

Depending upon many factors I don't see why you would have to have filters,
pumps etc if you introduced stickleback or mosquito fish (Gambusia) into
your pond. Both species are small with correspondingly small biological
output (they don't poop a lot). Both species are very adaptable with
respect to water quality. I see you are posting from the UK so I don't know
if it is legal to introduce Gambusia or other "exotics" into an outside
ecosystem but stickle backs are native to the UK so they should not be a
problem.

If you introduced a small numer into your pond they would provide mosquito
larvae control over the long term.

As an asside, who advised you that you need to introduce fish? The
municipality where I live has a long, successful record of controlling
mosquito larvae by using a targeted biological pesticide, Bacillus
thuringiensis serovar israelensis

This has no effect on other insects and is environmentally friendly.

So there may be options for mosquito control that either do not require the
introduction of fish, or if you can select the appropriate fish species they
will have a minimal effect on the ecosystem of your nature pond.
"Davy" wrote in message
...
I have been advised that I need some fish in my deliberately fishless
wildlife pond to control the mosquitoes. My neighbour has offered
sticklebacks. But now, probably because of the lack of fish, I have very
large numbers diving beetles and water boatmen on the surface - which I
would guess would eat any larvae.

I would rather not have fish cos I don't want have to have pumps and
filters
etc. Anyone any experience of how well my predatory insects might control
mosquitoes?

thanks

Davy