My question echoes that of below from an article on the Texas Butterfly Ranch blog:

"Why aren't they attacking the breeding sites?" Or are they? Is is not considered a good practice to pour a thin layer of oil on standing water?

More from the article:

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The aerial spraying of insecticides like Duet, the chemical dispersed last night over 106,00 acres of Dallas county, has not taken place since 1966. The Environmental Protection Agency and Centers for Disease Control and Prevention have said that Duet, comprised of synthetic pyrethenoids, are safe and pose no health risk to humans or pets. Descriptions of the chemical provided by Clarke Corporation say the chemical is even safe for bees.

Scientists and citizens expressed reservations about aerial spraying. The Dallas-area town of Lancaster even voted to not participate in the program.

Dr. John Abbott, Curator of the Entomology Collection at the University of Texas at Austin, questioned the effectiveness of such a measure. "All this will do is knock out the adults that are flying, but it doesn�t do anything about the eggs and larvae," he said.

"Aerial spraying will kill some, but not all adult mosquitoes, but it won�t solve the problem since the spraying will not impact the breeding sites," said Dr. Taylor via email. "Why aren�t they attacking the breeding sites?"

Dr. Mike Merchant, Professor and Extension Urban Entomologist at the Texas AgriLife Extension Service in Dallas, dismissed concerns of Duet effecting the Monarch migration. "I wouldn�t anticipate that Duet would have much impact on Monarch migrations or survival, " he said via email. "The insecticide lasts for just a few hours before degradation or evaporation." Merchant added that since spraying is done at night, butterflies would be less likely to encounter it and that studies suggest these insecticides are less toxic to larger insects.

"That said, we are taking a wait and see approach," he wrote.

Here is a link that might be useful: Texas Butterfly Ranch blog 8-17-12

They have been aerial spraying here since April. In addition to that, the trucks fog every night. I spray the sides of the house, shop, RV barn, and fences about every 6 weeks with permethiun, in the hose end sprayer, and put used vegetable oil from my propane fish fryer, on any standing water. The garden is absolutely covered up with honeybees, bumble bees, and carpenter bees, butterflies, and several hummingbirds. There are anoles, geckos, skinks, toads,and tree frogs everywhere.

The only negative I can report is that I believe the county contracts the aerial spraying to local crop-dusting companies, and last month when they aerial sprayed, it appears to me they had been spraying a herbicide and didn't wash out their tanks before spraying for mosquitoes. I have what looks like herbicide damage to every rose in the garden, and on the very tops of nearly every vine.

Jim

Well in Southern Dallas, it started pouring rain about midnight. So whatever residue there was must have been washed away pretty quickly.

Thank you Jim.

YES, they are spraying the breeding areas, they fog from trucks all the time in the Dallas and surrounding areas. They fog with MALATHION, which is an organophosphate, way more dangerous than a pyrethroid. Which are broken down by sunlight, chlorine in the water, bacteria in streams and lakes. It has to TOUCH the insect, which is why they aerial sprya when the mosquitoes are most active. Bees are in their hives, wasps are in their nests, neither should be impacted to any degree. I spray my chicken coop with pyrethrins and you can use it on the birds.
You don`t have to take off your shoes, wash your car, wash your patio furniture, it is not absorbed well by skin. You don`t have to turn off your ac or cover your house.

The funniest thing I have seen yet was the lady screaming at city council that she DRENCHES her kids in DEET and is upset they are spraying this POISON on her kid. Though why her kid is out in the middle of the night I have no idea. Look up DEET you idiot!

3 deaths,worldwide from pyrethroids, all from extremely concentrated and lengthy exposures, deaths from organophosphates? Thousands if not hundreds of thousands. DEET? Thousands, plus seizures, other medical problems.

They never should have told anyone. We are aerial sprayed and fogged all the time. I am here to tell you there is no impact here either. Lots of bees, wasps, aphids, whitefly, dragonflies, butterflies, moths, roaches....

I am surprised anyone in Dallas is still alive the way they have been carrying on, thought they all would have died by now. All we have been doing is fielding calls from angry Dallasites who don`t bother to find out the facts. My opinion of people living in Dallas has certainly dropped lately, one more person cusses at me for "dropping poison on me" I am going to SCREAM!
Tally Ho!

Why would Dallasites be calling you in Galveston, Tally? I kinda resent your lumping everyone together because not everyone here is like that.

Tally, thank you for the first-person account on aerial spraying for mosquitoes. MY main problem with it is that it ONLY kills the mosquitoes that it touches and does nothing for eggs and larvae. I have worried about the effects on beneficial insects and the wildlife. I have the same worries about street-spraying.

Personally, I try to avoid using anything containing DEET and will refuse to knowingly use any organophosphate pesticides. I "got" a kitten 9 years ago that had been doused with an organophosphate, he was a "seizure kitty" for the roughly two years that I had him, so I'm well aware of the dangers of organophosphates.

In any case, I feel the best control over mosquitoes is to prevent them from breeding. Which means removing any source of water that they can breed in OR putting a larvicide in pools that can't be drained. AND it requires that the humans pay attention to their surroundings and use repellants IF they have to be out while the mosquitoes are present. BUT, that requires people to be responsible for themselves, and some people seem to be unable to do that.

beachplant,
Thanks for your insults of everyone in Dallas.

I am personally against the spraying. DDT was "safe" back when they sprayed it on the population, and considered otherwise now. Duet is listed as having "no known" long term effects. I'd like to pass on that please, and last time I checked this was supposed to be a free country. It is also the least effective method of mosquito control as others have alluded to, only killing the ADULT mosquitoes which happen to be airborne and have a drop contact them on the way down - does nothing for the larvae.

We got sprayed last night, and I was one that was vocal in my opposition to the process. Why? Cause what's next....
When they discover this didn't work so well because it was so low impact, will they then decide to spray us with something more potent?
As far as "getting the facts", where do you do that? I see the local media asking questions of the manufacturer of the product used, and of COURSE they are going to say it is low impact, don't worry about it, blah, blah, blah. We hear what they want us to hear, and I've learned over the years that what we hear isn't necessarily accurate. I still say everyone should take responsibility for themselves. When did we lose our self sufficiency?

well I appreciate the responses, tho I too could live without the insults. I tried to ask an objective question and realize I might have phrased the question as to simply what effect the spraying might have instead of the 'how devastating' it might be.

I agree the spraying is probably generally safe with minimal
effects, and certainly the humans are at risk for west nile here. My garden still has bees and dragonflies; but is is also clear many of mankind's practices have been devastating to the environment. I think it is a good thing that more people are questioning our assaults on mother nature.

By the way they are spraying round two over the city tonight, which is designed to get the babies that hatched since the adults were killed in the first spray. Hopefully this one-two punch will do the trick this year and this will not become an annual practice in the future.

I wonder of part of the objections don't harken back to the 1950's when they would DRENCH us with DDT, all crops seemed to be dusted; and we thought nothing of it.

I agree that something needed to be done; who knows what the long term effects will be, as the people doing this obviously don't.

Agree that we don't need to be rude!

I work in a hospital that has seen several cases of West Nile. Trust me, whatever DEET, organophosphates, or pyrethrin can do to you doesn't compare to West Nile. It is a very ugly, miserable disease that takes weeks to recover from... If you recover at all. You have to weigh risks and benefits.

I heard them spraying last night. Two passes over my house. I hope they didn't miss!

I live in Delavan, Il. and they have been spraying for years and years now. For a long time there were virtually NO BUGS. No frogs, snakes or anything much that eats bugs either. I feel I live in a virtual DEAD ZONE. I hate to think of the impacts these poisons have had on me when I am out exercising and get sprayed with this garbage. Unfortunately, I can't get any help with this....nor can the bees :( They are going to destroy the planet with this crap.