Saturday, July 28, 2012

More War on Foul Insects: Mosquito Repellants

In my quest to find new ways to wage battle with the biting insects, I have been researching the new clip-on products, including the new Off! Clip-on.  I know I am not the only one who hates mosquitoes, because the mosquito repellant pages on my blog are among the most popular!

I found this research out of the University of Florida, on the Entomological Society of America website.  It looked at four clip-on devices, evaluating the repellent effect against the disease carrying mosquito Aedes albopictus.  The clip-on devices included the Off! Clip-On (contains pyrethroid agent metofluthrin), ThermaCell Mosquito Repellent (contains pyrethroid agent allethrin), and the natural products Lentek Bite Shield (contains geraniol) and BugButton Mosquito Eliminator (geraniol, lemon oil, citronella oil).  Interestingly, the pyrethroid containing products reduced trap capture by 41.7% to 77% while the natural repellents and placebo worked about equally.  Clearly the natural oils are not of much benefit against this mosquito (though they probably smell nice), and this is consistent with previous research on other mosquito species.
Orb-weaving spider spotted on the dock at Jim's Camp at Nistowiak Falls.  This is one of the largest spiders I have seen in northern Saskatchewan.  I put my finger in the picture to show size and I think it was making irritated gestures towards me with its front legs.
Pyrethroids are synthetic compounds similar to the natural pyrethrin, which is produced by Chrysanthemums.  The most familar one is permethrin, the agent applied to bed nets in malaria endemic areas.  They are toxic to bees and aquatic organisms, so should be used with caution and not released into bodies of water.  They are not applied to human skin, like DEET, and should not be directly inhaled.  However, pyrethroids are not toxic in low levels to humans and other vertebrates, excepting cats, because of an enzyme they lack.  Unfortunately though, even bed bugs have figured out how to be impervious to this insecticide. 

The clip on products are battery operated and run a little fan that distributes the insecticide around you like a cloud.  You would need to keep yourself stocked with batteries and refills of the insecticide to keep it going.  I've read anecdotes that it is not effective in extremely heavy mosquito areas, such as next to bogs and ponds.  Also, if you are moving around, you may leave your protective cloud behind you and may need to stay put for a few minutes to regain your "protective cloud".  Perhaps standing in one place and weeding may be useful, but putting it on the kids as they run through the forest may be futile.   

Also, the other issue is the effectiveness of these pyrethroid emanators against no-see-ums and blackflies.  Thein lies the itch.  I did try the device in the yard this past week.  We do have a high-mosquito level in our area and I did still get two bites.  I think it did manage to repel some mosquitoes though.  It does make a quiet sound, like someone running the vacuum cleaner three doors down the street, but is not bothersome.  I think I would like to use this device while sitting outside reading a book or eating, where the protective cloud could build up and have better repellant activity.  Anyone else using this?  


Alicia said...

I am really upset by the Off! Clip-on product and recommend that it is neither purchased or used by anyone. If you read the fine print you will see that this stuff is "toxic to bees." And since bees are one of the top pollinators you will eventually see a decline in the food supply. No pollinators - no food produced. And one of the recommendations is to use this product while gardening - give it a try. See if the garden flourishes when you kill off your pollinators. What an absolutely reckless product...I'm sure it was produced with just profits in mind.

Gardenista said...

Yes, pyrethrins are toxic to bees and I do hope to keep the bees around too! That it also why the Off insect repellant lantern thing is not of interest to me. It seems to create a room-sized area filled with the stuff. I don't even know about the human health of sitting in a cloud of that stuff.