What butterfly species are you referring to?

Gray Hairstreak and Painted Lady.

I think that Malva is listed as a host plant for both of those types of butterflies. I've had Gray Hairstreak caterpillars on green beans we had planted in the garden (I don't mind sharing with them) and also on Scarlet Runner Bean. I planted Malva sylvestris about ten years ago and have never gotten any kind of cats on it. I've only ever seen Painted Lady butterflies here a few times in all those years and have never noticed any cats on the malva. You could try it and see, I suppose. What works as a host plant at one person's place doesn't necessarily mean that another person will have luck with getting eggs and cats on that same kind of plant. I've tried planting a wide variety of plants hoping to attract the types of butterflies that I think I could get here. I might not have luck getting Painted Lady eggs but by planting Antennaria plantaginifolia I've raised many American Ladies over the years. I have lots of luck getting Monarch eggs but have never gotten any of the close look-alike Viceroy on the willow and poplar trees that I have (not that I noticed anyway). I'm very happy with what I've attracted here since I first started butterfly gardening in 2005. Now if I could only attract some Zebra Swallowtails to my paw paws!