~ janj wrote:

I read in a gardening magazine they're a waste to buy. They fly away once
released and the numbers in your yard or garden remain about the same.
They said the same thing for Praying Mantis.

This is what they claim in MG classes also. I found if you have a good
source (I had a heavily infested wisteria) and you follow the directions
on the bag, which say, wet source and release bugs after dark. They will
stay long enough to clean up the infestation. There wasn't an aphid left
to be found on the wisteria a week later.

Like any predators, they're not going to move if there's food to be had.
It's just that what we consider a major infestation, because it's damaging
perhaps just one plant, may not be enough to be considered a reliable
source of food for a hundred ladybugs.

In the summer of 2001 we had a major infestation of aphids throughout
Southern Ontario. We had a corresponding infestation of ladybugs
(generally Asian, not native - one of the drawbacks of releasing purchased
predators!). Most people didn't think that was too bad, but in 2002 we
discovered just what a single ladybug accidentally crushed in a wine press
can do to a batch of wine. It wasn't pretty :-) They release a chemical
that smells much like cat's pee.
--
derek