They seem to go for Verbena bonariensis, Hebe, Buddleia, Origanum laevigatum, Asters, Scabiosa, Lavandula and Rudbeckia in my garden. I don't know whether you can grow any or all of these?

I have a large white 'colerette' dahlia and it was teeming with insects, especially butterflies, all summer...:>)

sedum is very easy to grow there is a number of them you can have them allmost allyear the latest blooms december to april so if we get a day worm enough to wake them there is allways food for them ,and I have not seen anythingwith as meny butterflys on it, even betwen two ( buddleiua known as the butterfly bush.)