If you have an ornamental pool or landscape fish pond, you might be wondering how to reduce mosquito populations in these particular situations. Ornamental pools and landscape fish ponds are potential breeding sites, but they don’t have to be.
Below are some mosquito management tips for these pools and ponds. Some of these tips also apply to birdbaths.
Check for mosquito larvae and pupae at least once a week so you’ll know if mosquitoes are thriving and you need to start control measures. Simply kneel down by the edge of the pool, pond or birdbath and carefully watch the water for the distinctive wiggling of larvae and tumbling pupae. They are most likely found in warm, shallow areas. Since larvae and pupae must regularly come to the surface to breathe, just get comfortable and watch for a while.
One mosquito management practice is to stock the pond with fish. Healthy, hungry top-feeding fish can help control mosquito larvae and pupae. Smaller goldfish or koi generally will eat larvae and pupae, especially if the fish are hungry. If you notice wiggling larvae, stop feeding fish for a few days to see if the immature mosquitoes disappear.
Don’t over-feed your fish. Hungry fish make better mosquito predators. Also, by not over-feeding you won’t have leftover food to encourage algae growth.
Manage aquatic plants to keep them from providing mosquito hiding places. Plants in contact with the water surface might shelter mosquito larvae from fish or other predators. Thin plants or remove some so fish can swim around and through this vegetation. Avoid thin-leaved plants because they provide excellent shelter for larvae.
Mosquito larvae generally do well in stagnant water because they feed on the microorganisms. So periodically remove organic matter such as leaves, fruit and dropped flowers or buds that have fallen into the water. Excessive organic matter can require more oxygen than the pond has available for decomposition. The bacteria that grow in this situation discolor water and give it a foul odor.
Another mosquito management practice is to trim surrounding landscape plants away from the water surface so they won’t provide a base for algae growth as well as shelter for larvae. Another reason to prune landscape shrubs or trees is that all ponds and pools need some sunlight. Pruning reduces shade cover, thus enabling some light to reach the water.
Finally, avoid contamination from fertilizers, pesticides, herbicides or muddy runoff. Fertilizers can cause rapid algae growth in the pond. Many pesticides and herbicides used for yard pests can be very toxic to fish. If the yard will be treated for pest control, cover the pond for protection, or don’t have that part of the yard treated.
If you’re refilling or adding a large amount of water to the pond, consider whether the new water contains chlorine or chloramines. Contact a pet store that sells fish and nursery where you bought aquatic plants for advice on neutralizing these compounds. Generally, you can add small amounts of water, less than 10 percent of the volume, to your pond without a problem.
Tips for limiting mosquito breeding sites around the home
1. Dispose of old tires, buckets, aluminum cans, plastic sheeting or other refuse that can hold water. Empty accumulated water from trash cans, boats, wheel barrows, pet dishes, and flower pot bottoms. If possible, turn these items over when they are not in use.
2. Clean debris from rain gutters and unclog obstructed downspouts. Clogged rain gutters are one of the most overlooked breeding sites for mosquitoes around homes. Remove any standing water on flat roofs or around structures. Repair leaking faucets and air conditioners that produce puddles for several days.
3. Change water in bird baths and wading pools at least once a week and keep swimming pools cleaned and chlorinated. Ornamental pools can be aerated or stocked with mosquito-eating fish. Aeration / water movement helps, because mosquitoes prefer quiet, non-flowing water for egg-laying and development.