There is a small pond next to my house and I observed that dragonflies spawn there. Probably so do mosquitoes, at least the location in general is plagued by mosquitoes. Standing water is a suitable breeding ground for mosquitoes, but the dragonflies are an efficient predator.

How to estimate if the pond with its presence is contributing to mosquito growth or extermination?

  • Welcome to Sustainable Living! Could you please explain how this question is related to sustainability? As it is, it looks like it would fit better on Biology.SE – THelper May 22 '14 at 7:23
  • @THelper It is a better fit for Biology.SE. I saw a lot of mosquito questions here and thought this will be the right community to ask, and it was, I got excellent answers. – MKaama May 22 '14 at 7:33

At best, the pond is a local source of mosquitoes.

Predators such as dragonflies can only achieve a balance: if the mosquito numbers decline, so will the dragonflies.

If the pond cannot be covered or drained, I would encourage you to consider frogs, as Mσᶎ suggested. Worldwide, frogs are in decline, so introducing local species to the pond would seem to be a positive in sustainability terms.

But nothing comes for free: the dragonfly larvae will also be eaten.

While a few ordinary goldfish (or, as the Wikipedia article you linked says, guppies) will enthusiastically eat the larvae, they too will only achieve a balance. The total number of mosquitoes will be lower, but they will still be present.

Goldfish are omnivorous, so when they cannot find mosquito larvae, small crustaceans, or zooplankton, they'll eat vegetation and detritus. So they will not decline when the mosquitoes are eaten.

Unfortunately, any predator will also eat the dragonfly larvae, frogspawn, and tadpoles.

Other fish?
You do not mention your location, so we cannot know what indigenous fish could be introduced to the pond. It would have to be a species that copes well with still water.

In order of preference: frogs, local fish, cover or drain the pond. Avoid goldfish, since they are an introduced species and could escape.

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  • 1
    Note: Dragonfly larvae are properly called naiads. – andy256 May 22 '14 at 3:08
  • The pond can become almost dry during hot summers, so any kind of fish are not sustainable. There is a (audibly) vigorous frog population in the next, bigger pond and there are a lot of frogs in my garden, so they are sustainable. – MKaama May 22 '14 at 5:46

From your link it seems likely that you're seeing a net increase in mosquitoes:

dense populations can be useful in reducing mosquito problems

I take that to mean that you need a lot of dragonflies to see a small reduction in mosquito population.

My experience is that having a vigorous frog population eliminated mosquito larvae from the ponds the frogs were in, but we still got mosquitoes from surrounding areas. Comparatively few, but enough that we still needed screens and nets. Since flying mosquitoes have no effective predators, those seem to be the two effective approaches.

I suggest either frogs or insectivorous fish in the pond, or if that's not practical, cover or remove the pond.

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  • +1 for the frogs! – andy256 May 22 '14 at 1:01

Filling in the pond seems excessive. Mosquito's like stagnant water, rather than flowing. Install a solar powered fountain or fall. May not help but more attractive than a filled in pond.

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  • If it involves electric appliances, solar powered is very unsustainable. If you consider that wind is also solar-powered and a purely mechanical fountain can be designed, that would avoid big unsustainable industry up front. – MKaama May 23 '14 at 10:16

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