A backyard pond can be a breeding ground for pesky mosquitoes. In addition to carrying dangerous diseases, mosquitoes are annoying and can keep you from enjoying the personal oasis you worked so hard to create. Adding mosquito control tablets to your pond can stop the insects from maturing without harming your pond fish or plants.
Ponds and Mosquitoes
Mosquitoes breed in standing water, which means not all ponds make the best breeding grounds. If yours has a powerful fountain or pump that keeps the surface water moving constantly in all areas of the pond, you might not have a mosquito problem. Aquatic plants can block the flow of water and create small areas of still water that are enough for mosquitoes looking to lay eggs. The insects also prefer shallow water, so ponds with sloping sides are more at risk.
Easily available and affordable, pond tablets contain the bacterial insecticide Bacillus thuringiensis israelensis. The bacteria prevents mosquito larvae from maturing into adults. Mosquitoes must be adults to breed, so preventing the larvae from maturing effectively wipes out the population breeding in your pond. These tablets are often shaped like doughnuts and are easy to use -- simply drop them in your pond to float in the areas where the water is still. Each tablet covers a certain surface area, such as 100 square feet, so your pond might need several for complete coverage. This bacterial insecticide is safe for your pond plants and fish.
For larger infestations, you could need a stronger chemical. Although it might not be commercially available in all areas, methoprene is an effective mosquito-control agent for your pond. It comes in several forms, including tablets and bricks meant to be submerged. This chemical also affects mosquito larvae, preventing them from becoming adults. Methoprene can be dangerous to fish, so only use it if your pond is fish-free. It shouldn't harm your aquatic plants.
Mosquito tablets must be replaced during the insects' breeding season, which typically coincides with warm weather. Bacillus thuringiensis israelensis tablets and some methoprene tablets must be replaced every 30 days. Larger methoprene tablets, often referred to as bricks or briquettes, can last as long as 18 months underwater. For continuous coverage of your pond, replace the tablets when they are small, such as dime-sized, but before they are completely gone.
- Alameda County Mosquito Abatement: Mosquito Sources in your Backyard
- Alameda County Mosquito Abatement: Mosquito Prevention Considerations for Fishponds
- North Carolina State University Cooperative Extension: Mosquito Control Around the Home and in Communities
- Doctors Foster and Smith: Warm Weather Mosquito Control
- National Pesticide Information Center: Methoprene
- Cornell University Cooperative Extension Service: Methoprene
- Photo Credit Ryan McVay/Photodisc/Getty Images