Question from a reader.
"Do flower colors matter when choosing butterfly plants?
I thought I had read that the butterflies are attracted to bright colors."

The question you ask seems rather easy,
but the answer isn't.

Butterflies can actually see beyond our visual range, so color is a bit ambiguous.
What we see is not necessarily what they see.
Choose the colors YOU like.

While hummingbirds seems to prefer reddish flowers, you don't find this type of preference with butterflies.

The other factor you have to consider is that when you say butterflies, you may actually be talking about 100 different species in your area.
It's unlikely that one color attracts all butterflies.

I'd go with the standard butterfly nectar plants. See my list.

Also read my article about creating a Smorgasbord for your butterflies to dine on.

The more choices they have to choose from, the more likely they will be attracted to your garden.

While most Buddleia (Butterfly Bush) are purplish, I've actually seen many butterflies go to a white Buddleia.
It's all a bit subjective.

I'd say that nectar is a MUCH more important factor than color. If a flower has good nectar, then the butterflies will stay.
If the flower is a poor nectar source, even though it may be very colorful, like roses, butterflies won't go near it.