Have a white aphid or some insect on my daylilies. The lilies will not bloom and fall over.
Any suggestions on a control or pesticide? Thank you

Are the undersides of the leaves sticky? While it does sound like aphids, this would confim it. There are three ways to deal with aphids, two of which are chemical free:
1) chemicals like diazinon or malathion - use only if you don't have pets, veggies nearby or children. These are extremely toxic and nasty so shower completely after using. I don't use this method.
My grandfather told me these two methods:
2) brew up a very strong pot of coffee - gut rot. While it's cooling off, hose the lilies off with a hard stream of water. Let the lilies dry and then spray the coffee on the entire plant. The aphids get hyper and have little bug heart-attacks.
3) buy a bunch of lady bugs. Aphids are a ladybug treat. After the aphids are gone. The Ladybugs will find another home. Don't combine 2 and 3. We don't want to give the ladybugs heart-attacks.
As always, 2 and 3 need to be reapplied as needed.