My wife keeps her citrus trees in the greenhouse over the winter. This year, they had a really bad infestation of mealy bugs, which leave a powdery white residue on the leaves, as pictured in the link below.

https://hosting.photobucket.com/imag...080&fit=bounds

Does anyone have experience with this? If so, what is a good way to prevent it or destroy it? When we move the trees outside in the spring, the problem quickly goes away.

Thanks for any help,

Paul