British Columbia: White Flies

While cleaning up in the garden the past few days I have noticed a large amount of white flies on the undersides of the leaves on my rhododendrons. Any ideas, should I be concerned and if so what should I do, Thanks

 

Can't see the white flies in the pics. However...this is a really bad year for whitefly for me. I have them on things that have never borne a white fly in their lives, including some of my rhodos. I am assuming you mean the little white things that fly up as you touch the plant. Small & fairly fast flying, so sometimes you wonder if you saw them at all?

I half-heartedly spray the worst affected plants with insecticidal soap & assume that a hard frost will kill 'em.

What ticks me off is the herbs I like to keep for winter keep infecting other plants when I put them in the greenhouse. I chucked them all back out for a while, till they get cleared by the weather (hopefully).

gb

 

Thanks for the reply, yes as you described, fast flying, little white things. Usually only see them on the helleborus in my garden, but on many other plants, especially the lower branches of the rhodos.
Good idea about the frost, once we have a heavy frost I will have another look before I consider another line of action.