Preventing mosquitoes in water barrels

[ellen]

Here is the result of my research-
1. Mosquito Dunks seem to be the easiest and the most popular and
effective.
They float on water surface and kill larvae for 30 days. A pack of 6
costs about $10.00 at Lowes, Home Depot. They can be broken into
smaller pieces,and 1 or 2 packs of 6 would last our 4 rain barrels for
the summer.
SAFETY- Made with Bt-israelensis (Bt-i), a highly specific biological
pesticide, Will NOT harm people, pets, wildlife or fish.

However, as one customer points out-
"While the BT will have no negative effect whatsoever on your plants,
you might be introducing the BT-laced water into an environment where
it will harm the larvae of beneficial insects."
I don't know how serious this possibility is.

The dunks do float on the surface, so we would have to be careful not
to scoop them up when filling the watering can.

more info on dunks: http://www.planetnatural.com/site/mosquito-dunks.html

2. You can also install a fine-mesh screen across the top, but from
what I read this will reduce but not eliminate mosquitos. Some people
do this in conjuction with the dunks.

3. There are mosquitofish you can buy and keep in barrel, they are
effective - they eat the larvae, but I think the problem would be
scooping them up when we fill the watering can.

4. Longer-term solution - the best I think - is bat houses.
A single brown bat can consume as many as 1,000 mosquitos in one hour.

hope this helps.

[ellen]

PS - for standing water that is not being used for plants, a drop of
detergent is said to prevent mosquitoes from laying their eggs. fyi.