Pond Maintenance for Dragonflies

Pond Maintenance for Dragonflies

So now you have a pond. Yea! Here are some tips for maintaining a healthy, balanced habitat for encouraging dragonfly populations.

Controlling Algae

Before your aquatic plants become established (this usually takes about six months), your pond may experience a greater than normal abundance of algae. You may notice that your pond has a green hue - this is not harmful. The algae population will decrease as the aquatic plants mature. Essentially, aquatic plants will cool the water and use the extra nutrients that are making the algae population increase. If you want to aid the decline of the algal population, you can add floating plants such as duckweed and azolla; these plants will decrease the amount of light available for algal growth.

Accelerating Dragonfly Development & Reproduction

While you may see dragonflies checking out your pond, you may not witness the development of nymphs to adults within the first year. If your pond is located more than a few miles from the nearest wetland, it may take a bit longer for dragonflies to find your backyard oasis. To expedite the time frame for dragonfly development and reproduction, you may want to incorporate a couple of buckets of water and mud from a nearby pond or wetland. This will seed your pond with naturally-occurring aquatic invertebrates and plants. Do not introduce mud and water from a source that is not adapted to your local conditions or that might introduce non-native or invasive species into your newly created dragonfly pond habitat.

Once dragonflies have found your backyard pond, you may want to place a few stakes and branches at the pond margins. Until your pond landscape has matured, these stakes will provide a surface for nymphs to crawl onto for adult emergence.

Sediment, Debris & Invasive Plant Control

As your pond ages, it will fill in with sediment and debris, and may experience excessive plant growth. So a comprehensive cleaning routine every two to three years (preferably in winter when pond inhabitants are dormant) is important to to maintain the overall health of your pond. What to do?

  • Remove fallen leaves, and decaying plant material. Decomposition will decrease oxygen levels, thereby creating conditions that are more favorable for mosquito breeding.
  • Thin or remove plants that may be taking over your pond. Invasive aquatic plants should be targeted for removal. Your local natural resource agency can help you learn about invasive aquatic species. Herbicide should not be used to remove aquatic plants as it will decrease water quality and harm wildlife.
  • Scoop excessive sediment from the bottom of your pond.
  • Before discarding sediment and plant material, pile it near the edge of your pond for a couple of days. This is allow the trapped organisms to crawl back. Alternatively, you can place the sediment and debris in a bucket with pond water. Stir the contents of the bucket and remove and pond creatures that you see suspended in the pond water.

Mosquito Control

As the dragonfly and other predatory aquatic invertebrate (damselflies, copepods, water bugs, diving beatles) populations increase, they will be your established mosquito control system. If you suspect that you may have a mosquito problem, the first step is to sample your water to determine the presence of mosquito larvae. To manage mosquito issues, you may want to consider installing a small waterfall to increase water movement and discourage mosquito breeding. Experts do not recommend the following:

  • Installation of open water pumps without screening because they will suck in and kill dragonfly nymphs.
  • Introduction of the non-native mosquito fish (Gamusia spp.). They will eat many of your good aquatic invertebrates (as well as tadpoles and developing salamanders), and can quickly take over your pond with its rapid reproductive rate.
  • Use of "dunks" or briquettes of Bacillus thuringiensis israelensis (Bti), a biological control agent. This bacterium kills mosquito larvae but will also kill beneficial midges and crane flies. Again, balance is the key. Aggressive eradication of mosquito and midge larvae will decrease an important food source for many pond animals.

Maintaining the Optimum Water Level

When the weather is hot, you may need to add water to your pond regularly. You can use collected rain water or water from a hose. If your public water source is chlorinated, allow the chlorine to dissipate by setting out the water buckets for a few days. Just cover your buckets with a fine mesh screen to prevent mosquitoes from laying their eggs in the water.

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