About how to control mosquitos; using what
by Art Drysdale
by Art Drysdale


Art Drysdale, a life-long resident of Toronto and a horticulturist well known all across Canada, is now a resident of Parksville, British Columbia on Vancouver Island, just north of Nanaimo. He has reno-vated an old home and has a new garden there. His radio gardening vignettes are heard in south-western Ontario over radio station Easy 101 FM out of Tillsonburg at 2 PM weekdays.

Art also has his own website at

January 22, 2017

Above, the parts of a mosquito explained courtesy of Wikipedia Below, a case of one of the better mosquito repellants available in Canada from Doktor Doom.




Do you happen to recall about a couple of decades ago when there was a mosquito problem (I was in Ontario then, but I am certain it occurred all across the country) and health authorities and parent advisory groups etc. were strongly advising against the use of products containing DEET to prevent bites from mosquitos? Well, I certainly do.

Were back right now in a similar place due to the Zika virus, also spread by certain (probably not all mosquitos—[it needs to be discussed all over the nation because even though mosquito season is still months away for much of the country, the Zika virus infection has been found to be transmissible by common Culex mosquitoes, at least in a lab setting -- which means a whole lot of people in the north could be at risk as well].

Dr. Josh Bloom of the American Council on Science and Health in March last year wrote comparing Deet and DDT and the conclusions he drew are quite interesting.

“Since 90 per cent of mosquito repellents use Deet, I thought it might be worthwhile to write about what is Deet, some of its properties, and then to contrast it with DDT, a chemical with a far worse reputation.

“They are quite different, but not how you might expect.

“What is especially interesting about Deet is not that it is toxic (quite the opposite, really) but that it has the ability to penetrate skin rather easily. Depending on a number of factors (species, test method, type of skin, the presence of solvents) between 8 and 80 per cent of Deet that is applied to skin will end up in the bloodstream.

“That’s a lot.

“But after that, it behaves just like most other chemicals or drugs?it is metabolized by the liver, and excreted, mostly in the urine.

“Deet does repel mosquitoes, though with mixed results.

“DDT is, of course, an insecticide, and used to control [i.e. kill] mosquitoes. DDT also acts as a repellent when sprayed on surfaces.

“Although its use [was] and is prohibited in the U.S. over 40 years ago by the EPA, the world health organization still recommends DDT in malaria-infested areas such as Africa.

So why does DDT have such a terrible reputation in the USA?

“It has little to do with actual toxicity. One comforting thing is that Deet has a very low toxicity. It is not even a suspected carcinogen in a world where the international agency for research on cancer (IATC) can call anything a carcinogen --even sausage.

“We can say Deet is a safe chemical when used properly.

“But, it is still not recommended for use on children younger than two months, and products containing 30 per cent Deet or more are not recommended for children at all. That means the ability of using Deet as a repellent alone to protect our most vulnerable population is limited. Mosquitoes don’t care about age.

“DDT, on the other hand, is a repellent that also controls [i.e. kills] mosquitoes.

“And as I’ve written before it isn’t even remotely as harmful as its perception suggests.

“The prohibition of DDT was not even based on human health.

“Despite everything that you’ve heard about it, DDT was prohibited because of environmental concerns, which I won’t go into here.

“Despite all the cancer and other various scares, DDT’s toxicology profile reads much like that of a typical chemical or drug. And, of course, it has one big advantage for people worried about exposure to chemicals --it is sprayed on bugs rather than kids.

“There are other repellents and insecticides out there. And maybe Zika virus will be out there too, at which point some complicated, hard choices will have to be made.

“Some dark humor in the immunology community during the Ebola scare in 2014 was whether anti-vaccine parents were going to be first in line with bags of cash asking for a shot for their kids.

“Likewise, it may be that the loudest calls for more pest control products may come from chemophobic hypocrites, who don’t mind exposing a child to a disease as long it is not their child.

“So, DDT or DEET?

“Or something else?

“What is the best choice?

“We don’t know yet.

“It still depends on what happens in a few months.

“Stay tuned.”

All of the above is courtesy Dr. Josh Bloom of the American Council on Science and Health, and edited from the Pesticide website.


  • New Eden
  • Kids Garden
  • Plant a Row Grow a Row