Oh, right Howiah, I saw a small purple patch of Dame's Rocket outside today! I didn't know that butterflies love them; that's great. It's funny, as I passed by them, the word Hesperis came to mind - now, I wonder if that's their true botanical name & I've unconsciously retained it...sure enough, Hesperis matronalis. Funny things, our brains, eh?! (smile)
Halton Hills, I wonder if you might have seen a Swallowtail butterfly, perhaps a Black, Tiger, or Giant, or maybe a Great Spangled Fritillary? I know Tiger Swallowtails sure love our lilacs.
Tammy