Category Archives: Gardening

Bag of water hanging from ceiling

15 mosquito-control strategies and devices that don’t work

Health officials love to remind people to use DEET and other CDC-approved repellents, but they tend to shy away from telling the public what doesn’t work. As a result, millions of people adopt ineffective techniques and gimmicky devices. These people are not only subjecting themselves to annoying mosquito bites, they are increasing the likelihood that family members will contract West Nile virus disease, Zika virus disease, eastern equine encephalitis, and other mosquito-borne diseases. So I thought I’d make a list of the top myths and scams just in case skeptical people are Googling.

1. Mosquito-repelling plants

Despite the claims of thousands of posts on Facebook and Pinterest, there are no plants that, when planted around your yard, repel mosquitoes. And, just to be clear, the plant marketed as “mosquito plant” does not repel mosquitoes. I know this is deeply upsetting news to many plant fans. I’m just the messenger.

2. Ultrasonic devices and apps

None of these have been found to work (details). It’s too bad. It would be really cool if they did. The FTC has taken some companies to court. There is, however, a device called The Mosquito that is effective at repelling teenagers.

3. Bags of water suspended from ceiling

This belief is common in Mexico, Central America, Spain, and certain pockets in the U.S. south. It’s a variation of the equally-ineffective tradition of hanging bags of water to repel house flies. Some people insist that you have to add coins (and just the right number).

4. Listerine

Nope — even when mixed with other ingredients like beer and epsom salts, spraying Listerine around your yard won’t repel mosquitoes. Just another internet rumor started by somebody with too much free time.

5. Citronella candles

Citronella candles only seem to work if you surround yourself with a lot of them, ideally in a protected area so that wind doesn’t dissipate the smoke. Similarly, Tiki torches that burn citronella-laced oil are ineffective. They smell great, though. The pleasant smell most likely contributes to the strong placebo effect. People absolutely believe they work even though they do not.

6. Bounce dryer sheets

Per one study fungus gnats (which don’t bite) were mildly repelled by dryer sheets. I’d wager these sheets might actually be attractive to mosquitoes (some species home in on perfumes).

7. Wrist bands with natural oils

At best, wrist bands will reduce the number of mosquito bites on your wrist. But they will not emit enough volatile compounds to shield the rest of you. NB: currently there are no wristbands that contain DEET or other CDC-approved repellent. Details.

8. Stickers laced with natural oils

Stickers only prevent mosquitoes from biting the flesh directly underneath the sticker. You’d need an awful lot of stickers for full protection. If you can rock that look, I say go for it. Note, same conclusion for the stickers that claim to infuse your bloodstream with B1.

9. Garlic

Eating garlic does not deter mosquitoes. Just other people.

10. Vitamin B1, B6, or B12 pills or patches

Nope, nope, and nope. Details. More details.

11. Mozi-Q pills

Just another scam. Details.

12. Bug Zappers

These devices are adored by people because they make a satisfying crackle when an insect meets its end. Indeed, people who own these seem to delight in the attention these things get when friends come over in the evening. But if you dump all the carcasses on a table and sort them (good family fun), you’ll find that only a small fraction of the victims will be mosquitoes. In one study, 0.22% were mosquitoes. Mostly you’ve just electrocuted thousands of small, defenseless moths and night-active beetles. That’s a lot of bad karma. More details.

13. Dynatraps

These don’t appear to work. If you’re still on the fence read some of the many 1-star reviews on Amazon.

14. Tubes of yeast and sugar

Contraptions filled with yeast and sugar are really good at attracting and killing fruit flies, ants, and wasps. They will not control your mosquitoes.

15. Bats and birds

Sadly, it’s a myth that constructing a bat or bird hotel in your backyard will eliminate your mosquito problem. Bats and birds will certainly eat mosquitoes under some circumstances (e.g., when they are caged with nothing else) but under natural conditions they prefer to eat larger insects. You should still construct bird and bat houses, though. Details.

More information

If you have questions, email me.

Eliminate mosquitoes by eliminating stagnant water

The most effective, cheapest way to control mosquitoes is to eliminate the standing water that larvae need to develop. A dry yard doesn’t have mosquitoes. It’s really that simple. Below is a list of objects to get rid of or dump regularly. Please share with your neighbors.

1. Gutters

This is at the top of the list because almost all houses have gutters and almost all homeowners hate to clean them out. Check for blocked gutters weekly if you have a lot of trees nearby. If gutter status is hard to see, buy a drone to facilitate inspections. If you can’t afford a drone just get an extra-long, telescoping selfie stick for your smartphone.

2. Flexible downspout extenders

Flexible downspout extenders are perfect for mosquito larvae — the ridges hold water and the black absorbs heat from sunlight (thus speeding development). They are especially bad if nestled in shrubs and ground cover. Note that they hold water even if they are sloped downward. Get rid of them. All of them.

3. Tarps

If you leave a tarp in your yard, you’ve created lots of nooks in which water and debris will accumulate. I frequently see tarps covering soggy logs that owners seem to have no real intention of ever splitting into firewood. I think people view tarps as cloaks of invisibility, magically hiding loathsome to-do items from spouse.

4. Toys

Sandbox toys, sleds, wagons, and kiddie pools seem as if they were specifically designed to encourage mosquitoes. I.e., even when stored upside down they have nooks that collect enough rainwater to allow mosquito larvae to mature. Store them in the garage. If you think covering them with a tarp will work, please see #3.

5. Bird baths

Everyone should have a bird bath. But if you do, you need to either have a water bubbler/agitator (mosquitoes hate that) or you need to kill the larvae by adding granules of Bacillus thuringiensis var israelensis (abbreviated, Bti). Bti is extremely effective: you can add it a container that has thousands wriggling of larvae (see movie) and they will all be dead within hours. Just add it every two weeks and your bath will always be mosquito free. But don’t forget — make yourself a smartphone reminder or write on paper calendar.

Bird bath next to purple coneflowers

6. Trash and recycling bins

If you can’t store your trash and recycling containers under a roofed area, keep a lid on them. I found the ones below behind a local church. Tens of thousands of larvae within.

Recycling bins with stagnant water

7. Watering cans

Watering cans are rarely transparent so you can’t see the mosquito larvae inside, but they are present if you leave them around the yard when it’s been raining a lot. Store them empty, in garage.

8. Wheelbarrows

Just keep them propped up vertically so they don’t accumulate rain water. Or drill holes.

9. Rain barrels

Just put screening over the top. Or add Bti every other week. I don’t recommend adding mosquito-eating fish because they die when water level gets low (plus the fish suffer before dying).

10. Pot saucers

Pot saucers are unneeded outside so it’s easy to eliminate them. If you like them for decorative reasons you’ll need to add Bti regularly. It’s better to just get rid of them because you’ll eventually forget. You know you will.

Other places where mosquitoes larvae thrive

Other objects of concern are: pool covers, pot saucers, grill covers, plastic kid toys, tires, unattached hoses, empty glazed pots, shovels, construction materials, garbage cans, garbage can lids, containers in recycling bins, bottle caps, cemetery vases, decorative shells, empty coconuts, papaya tree stumps, downspout troughs, spigot drips, ollas, pickup truck beds, window wells, septic tanks, uncapped metal fence posts, animal tracks. Mosquitoes will also lay eggs inside in toilet bowls, animal water dishes, and French drains.

Alternative lawn signs for Mosquito Shield

Mosquito Shield is just one of dozens of companies that spray pyrethroids to kill mosquitoes. Homeowners typically pay $800 per summer for treatments spaced every 21 days and, as part of the deal, agree to feature a sign in their yard for the season.

Two types of people have these yard signs. The main category is homeowners who fully understand that pesticides have bad environmental effects but who simply don’t care. These are likely the same people who knowingly drive with their high beams on at night (“It’s safer for ME!”). And then there are people who were duped by the pesticide companies into believing pyrethroids kill only mosquitoes.

To better reach this second type of person as well as those who are interested in mosquito sprays but are still on the fence, I’ve fabricated six signs that highlight the fact that pyrethroids kill other animals:

All the signs are fairly self-explanatory except for perhaps the Bird Shield one. Pyrethroids don’t kill birds directly but many species depend on insects and spiders to feed themselves and their young. So when you hire Mosquito Shield to nuke your yard every three weeks you are reducing the numbers of birds that can survive in an area.

I realize that none of the above signs is going to be used by an actual pesticide company. Their business model is to obfuscate about the effects of pyrethroids. Indeed, most companies try to hide the fact that their mosquito sprays even contain pesticides. That’s why the government (federal and/or state) should require companies to clearly indicate the active ingredient of the spray. Here’s how it could (should) look, thus allowing curious neighbors to Google the chemical and be horrified.

Pyrethroid sign for Mosquito Shield

If you are an influential part of a local government, please consider enacting an ordinance that requires disclosure of the pesticide name on signs.

If you need an individual sign for your a presentation, here are some image files: fireflies, butterflies, bees, spiders, fish, birds.

Please share this page on your neighborhood social media to get the word out. These companies are spreading in popularity and it’s horrifying.

More details here.