The Bt dunks should be safe.

Add some cheap fish to the barrel

I scoop larva out of my water gardens & feed them to my Betas
+ You'll get the added bonus of fish poo

Can you simply cover the barrel so that the skeeters can't get to it?

People spray and/or dust their brassicas (cabbage, broccoli, cauliflower, kale, etc.) directly with BT to get rid of cabbage worms. So yeah, the treated water would be safe for vegetables.

Rodney

great info thankx

Empty the barrel, dry it out to kill the current batch, then install a screen on the barrel to keep mosquitoes from breeding in it.

Backyard rain barrels are a health hazard when mosquito-borne diseases are around: West Nile, Dengue, and Chikungunya are all lurking right at the border.

Agree. But no squiggles will survive if the barrels are emptied every 14 days, which is the life cycle of a mosquito larva. I do not have barrels, but I tip the bird bath and empty the watering can every 10 days or so. Same for seedlings trays kept outside, and for any other container. If done systematically, it decreases the number of mosquitoes locally.

But no squiggles will survive if the barrels are emptied every 14 days, which is the life cycle of a mosquito larva

Not true of all mosquitoes, and one of the most effective disease spreaders has a life cycle that can take advantage of your 14-day schedule.

http://entnemdept.ufl.edu/creatures/aquatic/asian_tiger.htm

Aedes albopictus overwinter in the egg stage in temperate climates (Lyon and Berry 2000) but are active throughout the year in tropical and subtropical habitats. Eggs are laid singly on the sides of water-holding containers such as tires, animal watering dishes, birdbaths, flowerpots and natural holes in vegetation (Hawley 1988). They are black and oval with a length of 0.5 mm.

Eggs can withstand desiccation up to one year.

Larval emergence occurs after rainfall raises the water level in the containers. The eggs may require several submersions before hatching (Hawley 1988). Additionally, oxygen (O2) tension greatly affects egg hatch (Hawley 1988). A number of studies have shown low O2 tension stimulates the hatching of Aedes albopictus eggs and is a more important factor than flooding or temperature on inducing egg hatch (Hawley 1988). Development is temperature dependent, but the larvae usually pupate after five to ten days and the pupal stage lasts two days (Hawley 1988).

http://entnemdept.ufl.edu/creatures/aquatic/aedes_aegypti.htm is also interesting.

Since I am trying to collect the rain water to water plants with I would defeat my purpose by emptying the barrels.

I am designing and making tops for the barrels. It wouldn't be hard to duct tape screen over the top but I want to be able to easily remove the screen so I can scoop water.
One of my ideas is to sew elastic into 'remay' cloth and see if that will stay on.
I am going to try elastic in mosquito screen also.

In the meantime I guess I will just wait out the cycle, if the squigglies mature but can't fly out they will soon die off.

Then empty them every five days. Once they are on the ground, they will not make it.

Glib, thank you for your ideas but my point is I want to use the water in the barrels to water the plants, if I dump it out I am without water until the next rain which could be weeks away.

minnows, then. Just leave one inch at the bottom when you empty them. They are 100% effective, and you can dump them in any pond at the end of season. Find them at any bait shop.

Apple, honestly.....the use of mosquito dunks makes the most sense of anything....even if you put a screen on top. Just make sure that you're using the mosquito control and don't get confused by Rodney's mention of caterpillar control....that's an entirely different Bt organism.

Fine for garden or dog drinking, the bacteria only attack larvae of certain species including mosquitoes and fungus gnats. The stuff they inoculate with the bacteria are usually corn cob ground up, so it is harmless to dogs.

If you're going to the trouble of setting up a rain barrel, likely you live in a climate where it doesn't rain all that much, so the idea of dumping out all the water seems to defeat the purpose.

I'd use mosquito dunks.

thx humbll good to know.

yes David I mentioned the same thing.

5 cent feeder goldfish available at any fish store ...

ken

[well they were ten cents back when i had a fish barrel]

Add used coffee grounds--confuses 'em & they drown.

Or you could put a lid on the barrel. Remove it when it rains and recover! A sheet of plastic or plywood would work.

I've used a few goldfish for 20 years. Never a squiggly. Don't even need to feed the fish.

paulyn, do you feed the goldfish? What do you do with them in the winter?

I have a screen on my rain barrel, but also have a few open five gallon buckets with liquid (compost tea, etc...) in them. I keep a plastic sieve next to one of them and every time I walk by or think about it I dip in real fast and scoop out the mosquito wrigglers. It's easy to get rid of them this way, you just have to be consistent about it until there aren't any left to lay the eggs.

I like the fish in a barrel idea, maybe Bluegills, Goldfish?

On second thought, not the goldfish, they're bottom feeders, go eith surface feeders like Bluegills.

I might try some fish just for fun for my grandsons but I think for me the most practical will be a screen cover.

We use the plastic sleeve the newspaper comes in to connect the end of the downspout to the hole in the top of the rain barrel, fit tight to both. We have an old wine barrel with a downspout-size hole cut in the top. Regards, Peter.

Peter, great idea thx!

Surface water used to be oiled with a thin sheen to suffocate mosquito larvae. You might experiment with some vegetable oil.

We did try the vegetable oil but it pools, doesn't produce that sheen that coats the surface. We use the dunks and they work great.