Re Tom's question about keeping mosquitoes down in a wading pool:
I've used doughnut-shapes 'dunks' of Bt (Bacillus thuringensis ssp.
israelensis) with success for the last several years in both deep and
shallow water tanks here (50- and 100-gallon stock tanks that are fed
by downspouts).
You can find them for sale online by searching for "mosquito dunk".
There's also granular Bt available. Best luck,
Nell Lancaster nlancaster@rockbridge.net
Lexington, Virginia USDA zone 6b