Spraying mosquitoes kills bees

Spraying your yard for mosquitoes kills bees.  It’s not so great for people either.

The “low-toxicity” pyrethrins and such that you can have sprayed on your plants (“Lasts almost a month! Kills ticks and fleas!”); or fogged in your garden throughout the day—are low toxicity for people and most animals, not insects.

Low toxicity doesn’t mean nontoxic, however.   A blog out of Duke University School of the Environment discusses how EPA approval is not a guarantee of safety.

Fogging creates mechanical human hazards as well.  “We entomologists are very much against timed applications,” University of Georgia professor Lee P. Guillebeau  wrote me.  “There may be no mosquitoes present, and there may be other things at risk. One report I read was a small child putting their mouth on the applicator; imagine the possible harm (and liability) if the applicator went off at that time.”

The chemicals are non-selective, meaning they kill all the insects they come in contact with, not just the ones we don’t like.  And while some mosquito-control companies advertise that they fog in the evenings when bees are resting, that won’t work here in Atlanta. The mosquito we are most concerned with is a relative newcomer, the non-native invasive Asian Tiger Mosquito, Aedes albopictus.  It flies and bites during the day, when bees and many other beneficial insects are also out and about.

Like our native mosquito, Aedes albopictus can carry diseases, including West Nile virus and Zika. Unlike our native mosquito, it can lay its eggs in very shallow water; even a jar lid or Southern Magnolia leaf will do. That is why it is sometimes called an “urban, container mosquito.” It only takes 5 days for an egg to reach maturation.  

Aedes albopictus was first found in the U.S. in significant numbers in Texas in the mid-1980s—it apparently arrived along with a shipment of tires. Ten years after it arrived, I noticed mosquitoes biting my hands during the day in Atlanta.  Before then, I remember our summer days being hot and sticky but relatively mosquito-free except at dawn and dusk. 

Sprays applied to foliage for longer lasting protection (“mosquito barriers”) are also non-selective, meaning that they too will kill beneficial insects —such as bees, ladybugs, assassin bugs, spiders—that are moving about on leaves. These are the same insects we are trying to lure back into our gardens for pollination and natural control of garden pests.

Chemicals cannot kill all the mosquitoes in your yard, nor do they kill only the beneficial insects in your yard. Insects don’t stop at your property line: they fly right over.  And most of them—including the Asian mosquito— have ranges farther than the typical dimensions of an urban Atlanta yard.

Nor will spraying your yard help reduce mosquito populations in your community: you will likely contribute to creating a “super” mosquito, resistant to the less toxic chemicals now in use.  Already, scientists have found mosquitoes resistant to permethrin, a synthetic chemical cousin to pyrethrum often used in backyard control systems.

Here we are, back in Silent Spring territory again.  We thought we’d learned our lessons when author Rachel Carson showed that DDT worked its way up the food chain, thinning out the shells of predator birds, wiping them out. Every time a hawk sails over our yard in Lake Claire, I marvel that I get to watch it.

Now we are losing our bees—European and native— which may be worse, if you count food as more important than the beauty of wild things.

“But,” you say, “My children are miserable.  The family can’t sit outside without being devoured.  I can’t garden without slathering up with disgusting chemical creams like DEET.” 

I believe we can develop a true, healthy solution when we say “no” to the same tired, dangerous routines.  It may be that it’s best to work with within boundaries–like using a porch fan, for instance, rather than trying to air condition the city.  And it is likely that those fogging their yards think this is what they are doing.

As Professor Guillebeau  wrote me later in the same email, rather than using pyrethrins, however, “it is much better for a neighborhood to work together to eliminate breeding sites.”

Following are some possibilities:

Walk your property weekly to locate, tip, clean, or remove containers that can act as breeding sites:  toys, wheelbarrows, trash, tires, saucers under pots, clogged gutters, drop inlets with shallow reservoirs (most are made this way), hollow trees.   Do this with a neighbor:  we don’t see our own stuff.

My neighbors use an outside fan and citronella candles to keep mosquitoes away.  They throw big parties, so I guess it works.

Share a leaf shredder with a neighbor or community and use it to shred fallen Southern magnolia (Magnolia grandiflora) leaves.  These leaves can hold enough water to breed mosquitoes when it rains all week.  

Buy organic mosquito dunks impregnated with a mosquito-specific bacterium for use in flower-pot saucers and other areas that hold water.  Lowe’s carries them.  You can also add a bit of vegetable oil—cheaper but stickier—to standing water, which will suffocate the larvae.Adding bat houses won’t help with the Asian mosquito because our bats fly at night; but they will help with the native Southeastern mosquitoes.

I read an intriguing ad for a mosquito trap that might work since it attracts using CO2. 

Finally, pyrethrum, the natural derivative of the Asian chrysanthemum flower, was almost certainly a traditional solution to the problem.  I wonder if there is more recent research–into other natural or ecosystem controls of the Tiger Mosquito.  Perhaps those with access to restricted science journals, fluent in Asian languages or experienced with life there can share with the rest of us.