Answer: White or green critters on the new growth are probably aphids. You can wait until ladybugs find out they are there and come in droves to feed on them, or you can spray the aphids with insecticidal soap. Cutting off the foliage is a bit drastic. Aphids are common on new growth and you can discourage them by hosing them off with a strong stream of water, or with applications of insecticidal soap. Best wishes with your wisteria.
Q&A Library Searching Tips