Mosquito Repellent

A side discussion at the General Meeting Tuesday night involved the new OFF Clip-on mosquito repellent. I bought the product today to test, and I did some research on the active ingredient, metofluthrin. Metofluthrin is a relatively new synthetic pyrethroid, that is, a substance with a similar chemical makeup based on the naturally occurring chemical pyrethrum, found in a certain species of Chrysanthemum - Chrysanthemum cinerariaefolium. There are several different compounds on the market today that are chemically similar: permethrin, resmethrin, pyrethrin, etc. As a general rule of thumb, if the active ingredient on the label ends in –thrin, it’s in this category of compounds.

The active ingredient that I use in mosquito control operations (Ultra Low Volume sprays) is usually permethrin. Permethrin is also used as a repellent in hunting and camping gear, and in mosquito bed netting in tropical regions to prevent malaria. It is sprayed or impregnated into the clothing, not on the skin - an important distinction. It is the active ingredient in several over the counter treatments for head lice, as well.

Pyrethroids fall into the category of Botanicals, if you remember your IPM training, although sometimes a distinction is made between the synthetics and the naturally-occurring compounds.

Metofluthrin seems to be more volatile (it evaporates into the air more readily), than other compounds in this category, which probably (I’m guessing) is the reason Johnson and Johnson chose it for this application. Here are the pertinent links about the product:

Product Description from the supplier, Johnson and Johnson.

US EPA Fact Sheet on the active ingredient.

Here’s a product review (and a good discussion about mosquitoes) from a Michigan State University Entomologist. Scroll down to The summer of our discontent item in the newsletter. Excerpt:

A recently available personal barrier repellent, OFF clip-ons, also uses a pyrethroid type of insecticide (metofluthrin) dispersed with a small fan as a repellant. I recently tried using one of these units, but it was ineffective against the swarms of A. trivittatus that attacked my dog and me when we walked near the edges of the lawn or along country roads. It did appear to inhibit landing/biting attempts when I used it while sitting on the patio, but it did not eliminate repeated mosquito attacks to my head, face, and lower legs. I doubt most people will want to wear three of these units for full “coverage” and I suspect no one will want to wear one as a necklace to keep A. trivittatus away from the head and neck – the packaging label warns against inhalation of the vapors (something that’s probably hard to avoid, in my estimation). Unfortunately, there are no great options for barrier repellants yet. Landscaping plants and citronella candles have not been shown to be more effective than smoke producing candles in keeping mosquitoes at bay. However, research of area-wide repellants is a hot area, so expect to see more products of this type in the next few years.

A recent review published in the Baltimore Sun from an LA Times columnist.

Off! Clip-on is unlikely to offer much relief to hikers or golfers or any other active people in mosquito country, Paskewitz says. As the product website warns, "if you move, allow a few minutes for the unit to rebuild its protection." In other words, it works best if you stay in one spot. "This sort of thing might be helpful if you're reading a book on a patio," Paskewitz says. "I wouldn't even bother trying it for backpacking."

Linda S. found it very effective keeping those pesky gnats away while picking black raspberries.

Additional Johnson and Johnson information.

This PSU handout has some excellent general information on insect repellents. And here are the CDC and EPA links on them.

Here are investigations into some of the home remedies for mosquito repellents you may have heard about. Snopes. Rutgers University. University of Wisconsin.

I've been bothered a lot by the gnats this year while gardening, so I plan to use it and see if it provides relief. It does appear to be a popular product in terms of sales.

As always when using pesticides (repellents are classified by EPA as pesticides), read the label and follow the directions.