Mosquitoes and Standing Water

Eastern Pondhawk 

The wetland I created with a pond liner does not have standing water. It was not designed to be that kind of wetland. When it rains, as it did a few days ago, the water is directed into it from the rain gutters and the drain spout off the corner of my roof. The water saturates the soil and keeps the plants wet, but excess water exits the wetland on the side away from the house. There is a slight slope and this protects the foundation of the house from these conditions.
The other wetland I created over a year ago, uses a plastic pool and it does hold water after a rain event. At times like these, the water evaporates after 3-4 days, but during the summer rainy season, it almost constantly has standing water. This creates both positives and negatives.
The negatives are all related to the fact that standing water breeds mosquitoes and that mosquitoes breed disease. Regardless of also having dragonflies and their larvae present in your landscape, having a standing water source encourages mosquitoes to breed and no amount of predators will keep them fully under control. Mosquitoes have an amazingly quick life cycle from egg to adult. The whole process from egg to adult can occur in as little as 1 week, so standing water of any kind will generate these pests if it isn't changed or if it doesn't dry up during that time.
The issue lies with the other living creatures that also depend on free-standing water. In a living landscape, like I am trying to create here, I welcome the chance to produce frogs, toads and dragonflies.  All of these need standing water for several weeks or more. i cannot change the water and keep the tadpoles and insect larvae, nor can I treat the water with something like bleach.
The balance comes from using an insecticide that targets the one and leaves the others alone. We live in a world where the pendulum is rapidly swinging from one extreme to the other. When I was a child, insecticides were touted as the savior of the human race. We applied them liberally to everything. If we saw a bug, we were prepared to kill it without question. During the past decades, we have pretty well succeeded in wiping out a majority of invertebrates that once shared our suburban parks and yards. With this realization, came a rapid shift in the pendulum to the opposite extreme where the use of any control method is derided by good environmentally conscious people. Truth is, it's not so simple. If we have standing water, we will have mosquitoes and the very real threat of disease transmission. If we continue to wholesale spray insecticides from the air and from the back of truck-sprayers, we will have the wholesale slaughter of every invertebrate that makes contact with the spray. Last fall, every pollinating insect that was using my yard disappeared overnight and this was most likely caused by a mosquito control operation in my neighborhood.
There are environmentally conscious insecticides for mosquito control. It's just that most governments continue to use that what they know and what is cheapest to use. When the water in my plastic pool stands for more than 3-4 days, I use one. The trade name for the product I use is "Mosquito Dunks" and it is marketed by a large number of companies. Dunks release a bacteria (BTI) that is only toxic to mosquito larvae. It partially dissolves when floated on the surface of the water and it works for up to 30 days. It does not harm the tadpoles or the dragonfly larvae that also use this water during the summer months.
There are mosquito larvicides that can be used in large-scale operations such as are used by governments. One can only hope that a more-enlightened government regime will surface out of this present day one that largely disregards the lives of other aquatic creatures.