Tag: Ponds

Proper Water Garden Maintenance

©Marlene Condon

October 3, 2020

Dragonflies, such as this female Widow Skimmer (Libellula luctuosa), mate at ponds and leave behind fertilized eggs from which aquatic larvae hatch. Help these young insects survive winter by keeping most of the muck at the bottom of your pond. Courtesy of Marlene A. Condon

If you have a water garden situated at ground level, you’ve undoubtedly created a home for a variety of wildlife. Therefore, it’s not a good idea to thoroughly remove the water to get all the muck out from the bottom of your pond every fall, as advised by most books and garden centers. Water insects (such as dragonfly larvae and water striders), frogs (adults and tadpoles), and salamanders (such as Red-spotted Newts) require this organic substance that builds up over the course of the year in order to safely hibernate out of sight of predators.

Instead, reach down into the pond with a plastic measuring cup to scoop out just a bit of it each year. (Be sure to wear gloves, such as those made for doing dishes). This material is extremely fine so bring the cup back to the surface as slowly as you can to avoid clouding the water. It’s easier to see what you are doing if the water remains clear. Your goal is to keep the pond no more than about half-full of muck.

Although dead animals and decaying plants or plant parts (such as leaves) can deplete the water of oxygen and cause a change in the pH, you don’t need to find every single bit of plant debris. Take the big pieces that are easy to net or grab with your hands and forget about anything smaller; it serves as food for numerous organisms (such as aquatic worms and snails) that transform it into the muck that benefits so many kinds of critters.

Always place the objects taken from the pond into a basin (I use an old dishpan) so you can check for animals before bringing it to your compost pile. (If you wear reading glasses, you may need them for this task). I carefully check everything (such as leaves and twigs) as I grab them from the dishpan one by one to place around shrubs to decay. If creatures are clinging to the plant debris, I can return them to the pond. Some critters follow the water from the draining plant matter to the bottom of the dishpan. I pour them back into the pond after I’ve taken out all the leaves, twigs, etc.

If your pond has attracted wild animals that have made it their home, you undoubtedly have achieved a balanced ecosystem that can function effectively practically on its own, just as natural ponds must do.

Sadly, in our modern world, wetlands — large and small, permanent and temporary — are often treated as nuisance or undesirable areas. They are drained, filled in, or otherwise destroyed, leaving aquatic animals high and dry. Salamanders and frogs that need these habitats to survive are either killed or forced to locate to another wet area, but this is increasingly difficult for them to do. Our wildlife is losing ground, literally, but gardeners can help by making their artificial ponds welcoming all the year round to our wild critters.

Be proud of your oasis for wildlife!

Winter Temps and Insect Numbers

© Marlene A. Condon

October, 2012

The author has two small artificial ponds on her property that teem with numerous kinds of critters (such as this Green Frog), many of which feed upon mosquito eggs and larvae. (Photo: Marlene A. Condon)

People have the mistaken idea that cold winter weather kills insects and other invertebrates, thus limiting the numbers of these animals by the time spring arrives. But if it were true that harsh winter temperatures kill these critters, there wouldn’t be any of them at all in areas north of Virginia, where it typically gets much colder every year than it does here.

These animals need to make it through freezing conditions to perpetuate their kind. If they hadn’t figured out how to survive such conditions, they would have gone extinct by now. Therefore it’s actually adverse spring and summer conditions, such as drought, that are more likely to negatively impact the number of invertebrates each year.

Conversely, folks tend to think that mild winter temperatures will increase invertebrate numbers, but, in fact, this situation can be deadly. Many kinds of hibernators, such as insects, may die if they become active during the winter in response to warm temperatures because there simply isn’t going to be much food available for them. The lack of food at this time of year is one of the reasons they need to hibernate.

In 2012 the Centers for Disease Control blamed mild winter temperatures for the faster spread of West Nile Virus by mosquitoes. However, in a naturally functioning environment, such a scenario would be highly unlikely to happen.

If it’s warm enough for mosquito eggs to hatch or mosquito larvae to become active in ponds or still areas of streams, it’s also warm enough for their aquatic predators to be actively feeding upon them.

The result is that few mosquito larvae would be able to survive to adulthood, only enough of them to maintain the proper functioning of the environment. And, of course, adult mosquitoes would also be taken by predators, reducing the numbers of mosquitoes available to reproduce. The same holds true for artificial ponds in your landscape, as long as you allow them to work naturally.

If, however, you instead treat a pond as an aquarium that gets cleaned out every year and perhaps has chemicals added to it, wildlife will have difficulty surviving within it—and that means you won’t have your natural system of checks and balances to keep the pond (and yard) functioning properly. Under these circumstances, of course, you may indeed help mosquitoes to proliferate.

Other common ways in which people create breeding habitats for mosquitoes is by leaving standing rain water within gutters that need maintenance, kiddy pools, toys left outside, and tarps over outdoor furniture. Water features that function as gardens only (i.e., they are used only for growing plants instead of functioning as genuine ponds full of life) are problematic as well. These areas will usually be devoid of animals that feed upon mosquito eggs and larvae.

As for bird baths, they should be emptied every day and fresh water put in. It should be obvious that you need to replace the water daily because birds leave behind visible waste and debris. Yet retailers advertise mosquito dunks to use in birdbaths, even though this pesticide is totally unnecessary. It’s also not as harmless as many folks believe.

Mosquito dunks are composed of Bacillus thuringiensis subspecies israelensis, a bacterium that specifically kills mosquitoes (and their close relatives). Although this pesticide is touted as nontoxic to humans, if bacterial spores are inhaled or rubbed onto the skin, they act as foreign proteins and can cause allergic reactions. Thus Bti should be handled with care.

Additionally, studies have shown that Bti, which is used in spray programs, could be more persistent in the environment than previously believed, with the potential for bacterial proliferation and thus an increased accumulation of these bacteria in mosquito habitats. Such Bti persistence would lengthen the amount of time that organisms are exposed to the insecticide, increasing the risk that target insects could acquire resistance to it.

Bti spores have also been found in untreated areas, raising the concern that microbial insecticides can spread, causing ecological harm.

If homeowners were better about correcting the conditions on their properties that allow mosquitoes to increase in number, localities could do away with large-scale pesticide-spray programs that many citizens and all health departments demand, but which pose threats to the environment.

Additionally, if most folks weren’t constantly trying to banish practically all wildlife (except perhaps birds and butterflies) from their yards, they would not be faced with the need for pesticide usage in the first place. This is exactly the wrong course of action. Without a variety of organisms in your environment to keep populations balanced, you end up with overpopulations that can’t help but be pestiferous—to themselves as well as to people!

The reality is that we cannot change the way the natural world works. Instead we must change the way we live.

Blue Ridge Naturalist: Winter Temps and Insect Numbers