Nature Notes: Mosquitoes

Mosquitoes are so populous, not even their natural predators can help control their numbers.

W hat eats mosquitoes and how can we prevent, deter and help control the population? I have been asking myself this question for several weeks.

With summer in full swing and the temperatures rising, so too is the population of mosquitoes. You can hardly walk outside without getting bit by the little bloodsucking vampires. It made me wonder what naturally eats them and what we can do to help control them, aside from all of the spraying by trucks and airplanes and using insecticides that aren’t good for the environment or our own health.

I used to think bats ate a large portion of mosquitoes, but I discovered this is a common misconception. Last summer, I went to Old Tunnel State Park in Fredericksburg and learned that while the Mexican free-tailed bat can eat up to two-thirds its body weight in insects every night, they mostly catch and eat moths while flying. In Houston, there are a couple of places where you can find these bats, including Watonga Boulevard Bridge, White Oak Bayou Greenway Trail and Waugh Drive Bridge. So while it’s true bats eat mosquitoes, they don’t eat enough to help control them.

We do know birds eat mosquitoes and their larvae. Yay! There are a lot of birds around. Purple martins are thought of as mosquito-eating machines, but sadly that’s not true either. They eat a diet of all kinds of insects, but mosquitos are a smaller part of their daily diet. Also, once purple martin chicks fledge, they pre-migration back to Central America and by September they are gone. Other birds that routinely dine on mosquitoes are swallows, songbirds, ducks, geese, nighthawks and terns. Sadly, they just don’t consume enough to make a dent in the mosquito population.

But wait, dragonflies eat mosquitoes too. There are many different dragonfly species in Texas, but how many mosquitoes do they eat? Turns out one adult can eat up to hundreds of mosquitoes a day. And dragonfly larvae lives under water and consume a lot of mosquito larvae.

Fish also eat mosquito larvae. Guppies, minnows, koi and goldfish eat mosquito larvae, but there’s a fish that really thinks they are tasty — the Gambusia affinis, known as the mosquito fish. Sounds good just by the name. They are a native fresh water fish found in canals, rivers and also are used by garden enthusiasts to help keep ponds from becoming a breeding ground for insects. Dragonflies and fish are great at helping control the mosquito population, but they can only eat so many.

We’ve learned mosquitoes and their larvae do have some natural predators, but it’s still not enough to keep us from being eaten alive some parts of the year, so what else can we do to help control or prevent them? Start by keeping birdbaths clean and refilling them with fresh water daily, washing out and refreshing our pets’ water bowls, removing any standing water around your home, and planting flowers and herbs that are natural mosquito repellents such as marigolds, lavender, citronella/lemon grass, rosemary, basil and scented geraniums.

There also are oils you can use to repel mosquitoes. Lemon eucalyptus is supposed to work as well at preventing mosquito bites as DEET in low concentrations. Others are lavender, cinnamon, thyme, citronella and tea tree oils. Keeping lawns mowed also helps some.

The bottom line is even with all the natural predators, plants and oils, unfortunately the only way to help control the population is with insecticides. This comes with a price, however. Mosquitoes are bothersome and can carry diseases, but we also have to remember they are necessary in the natural world. If they disappear, bats, birds, bugs, fish and other things in nature would suffer. Chemicals used also can be harmful to many other living organisms, including us humans. So, while it’s definitely nice to have fewer mosquitoes, we don’t want to go overboard with control.

Denise Stephens is a volunteer at the Gulf Coast Bird Observatory. The GCBO is a non-profit organization dedicated to saving the birds and their habitats along the entire Gulf Coast, and beyond into their Central and South America wintering grounds.

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