My Nasturtiums up until this morning had good healthy leaves.However when I
looked this morning several of them have white blotches on the leaves and
some of these were partly eaten.

Are the white blotches due to aphids or similar pests and if they are can I
spray my other healthy specimens with a bug spray ?

I have uploaded two pictures, one of a good plant and blotched specimens.
Sorry about the quality. http://tinyurl.com/rhxv6

Any info on this attack would be welcome as last year I had nasturtium
flowers which lasted all of one week and the plants all died a week later.
This is putting me off trying again next year.

M