Ron, I would cut all this foliage back to just above the ground and clean out all the dead foliage around these daylilies. Throw this foliage in the trash and not on a compost pile. The whitish insects are aphids. You should then spray what is left of the daylilies with an insecticide for aphids that you can get at Lowe's, Home Depot, Walmart, etc. It is a good sign that new growth is coming out of the centers. You might check to see if the aphids are also on your other daylilies and then spray those too.
