Will anti-mosquito treatments be harmful to my bees?

Hi, I am new to beekeeping and we’re really excited about our Flow Hive 2! I am going through a class now with a friend and we’re starting our hives together. Just put the nuc in today when it occurred to me that our mosquito treatments could be harmful to the bees.

My wife and daughter have bad reactions to mosquito bites, so we have our yard sprayed to repel them, typically every three weeks. I checked with the company and they use “bifen i/t, mixed at a rate of 100 gallons of water/ 96oz of bifen. So very diluted. We do not treat any open blooms. Our treatment is not harmful to bees.”

I did a preliminary Google search, and found only two answers, one that said it could hurt bees, and one that said it would not hurt bees. Hoping someone can add some more color.

Thank you for the help!

Bifen is a pyrethroid. Definitely toxic to bees imho :cry:


The bifen does not repel the mosquitoes, it kills them. It also has latent effects that last (more than 3 weeks) but maybe not at that dilution

The bifen kills many other insects too, some beneficial, some not. The mosquito spraying company is unfortunately not a reliable source of information.

Page 5 of epa label sheet:
“ This product is highly toxic to bees exposed to direct treatment or residues on blooming crops or weeds. Do not apply this product or allow it to drift to blooming crops or weeds while bees are actively visiting the treatment area.”


Maybe your technician is more careful than most but the way they spray it, it will assuredly get on flowers and plants that the bees will come into contact with. Also, the bees land on all sorts of surfaces to forage for water. If you really want to continue with the mosquito spraying then you should ask them to come after dusk.

Maybe see how will a bottle of picaridin 20% repellent spray does to prevent bites? I also react to mosquitos (and bees) pretty severely and if I am diligent about applying repellent - I do really well. The picaridin seems to work better on the Asian tigers than the DEET.

How big is your yard? Where in NC are you?


Hi @scorch088 and welcome! Congrats on your new bees and Flow hive :sunglasses: Your realization and deeper curiosity shows you are already thinking like a beekeeper. Finding & using alternatives to the pesticide spray will be well worth the effort.

Awhile back I bought a device called the Bite-Away pen, because although I’m not allergic bee stings swell up & get very itchy on me. It’s very effective and also works for mosquito bites. We also have one of those zappers - we hang it out at dusk whenever we sit outside during mosquito season. Fire pits are handy too :+1:


Mosquito dunks are safe if you know what water sources they are coming from. They also make some very effective traps these days.


And let’s not forget to raise a glass to bats - always happy to see them flitting across the sky on a warm evening :bat::bat::cricket_bat_and_ball:


If you’re in an urban or suburban environment, unfortunately every neighbor probably has standing water in gutters, flower pots, pet water bowls, etc and the mosquitos will gladly travel a few hundred feet for a meal. Spraying your yard for mosquitos is only effective for the wallet size of the company that does the spraying…


I put up a bay house last fall now I’m hoping to find some occupants in the next few weeks. I think one of my neighbors has bats in their attic that they are planning to evict so maybe my bat house will take in the homeless!


Thank you all for the feedback! A few things to add:

  • I am in Hillsborough, NC
  • We have a fairly big lot for residential, .7 acres and the mosquito treatments have worked really really well over the last year of doing them, have only ever seen 1-3 of them… in a year
  • We spend a ton of time outside all over the yard and my daughter has sensitive skin so hesitant to do bug spray every time
  • We do keep the bees just outside the fence, about 15 feet, in the back of our yard

You’re probably spread out enough that the mosquitos from other yards aren’t coming over, so the treatment on your yard is effective - because it is very toxic to insects.

If you’re only seeing 1-3 mosquitos in a year then they probably don’t need to spray as much or as often… they’re supposed to use the minimum necessary to obtain a reasonable result… I’d say they’re easily past an expected result.

If your bees are outside the treatment area and separated by a fence then you might be fine, but keep a close eye and make sure the technician knows not to spray near them.

Picaridin is gentler and less smelly so I’d still recommend trying it anyway - try the back of the hand or a spot on the leg first to see if there’s any reaction.

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Thank you! Does anyone know if that dilution (96oz in 100 gallons) would make it less harmful to bees? They say it “dries in 30 min from wet.”

I clarified to them that I do not want them to spray the ~40 ft behind the fence where the bees are.

I would refrain from using any insecticides on the yard personally. Seems risky. Especially if there are dandelions, clover, etc.


I’ve been using mosquito traps that emit a CO2 plume to attract the females for about 10 years. They use a simple fan to suck them inside where they perish. Toxin free and wipes out an acre or so of mosquitoes. It does kill moths too, but no effect on bees. There are multiple breeds of mosquito that emerge at different times of the season, so it takes a couple of seasons to wipe out the life cycle of all of them. You’ll notice a marked reduction in mosquito bites within days. The current one I’m using is Ambush. Works very well and cheap to run.