I do, Leo. The roots of butterfly host and nectar plants benefit from having a mulch over them just as much as other plants do. I keep a "Things to Do" list, and the next thing on my list for me to do tomorrow is to add leaves around my garden plants - summer is coming up, with 90 degree temps, so mulch will be important for the next 5 months or so. In early spring, when temps are beginning to warm up, I'll frequently pull the mulch back away from the root zone around a lot of my plants, so the soil can warm up quicker, but then I replace it in late spring and add more mulch in early summer.
MissSherry

I mulch everything...., now-as I live in the south, I use 2 kinds of mulch.

Pine straw mulch, which I run through a shredder (makes it much nicer, softer, and workable). I do this because you should never have a wood mulch on a bed that touches your house (termites)

I am now using a double hammered oak mulch in my other beds. If I buy mulch in bags, I shred that too. It really holds down weeds, keeps the soil warmer in winter, and brings earthworms to the surface, all of which are good. And of course, it lessens my weed pulling!