I have butterfly bushes that do not have any leaves yet
The winter was severe. They do not have any leaves yet and it's 04/26/14.
Butterfly bush (Buddleia davidii) is a very large group with many cultivars, all of which are not reliably hardy in zone 6. You do not mention how long you have had this plant, but it's possible that the winter was severe enough to damage it, and you might still see new growth coming up from the roots. On the other hand, it may have died. There are plenty of other varieties you can try. This article has some more information: https://www.ipm.iastate.edu/ipm/hortnews/2002/2-22-2002/butterflybushes.html