Whitefly on Greenhouse Tomatoes

Tapping the canes, to shed the pollen, today I saw a few whitefly take flight

I have always had them, so likely they have overwintered (assuming they are able to do that?).

I have planted a French Marigold at the foot of each Tomato plant which I hoped would do the trick ...

What next please?

Insecticide? Predator? SB Plant Invigorator? Yellow sticky traps?

I expect I have some pesticides and SB Invigorator lying around, anything else will have to be "ordered in"!

Thanks.

Do the yellow sticky traps work outside too?  I planted out some brassicas today and they immediately were drawn to them.

To they do alot of damage?  Sorry if that's a daft question.