I believe it is an Eastern Black Swallowtail.

Compare it to the photo I've linked below. In the wiki link below, scroll down to the Morphology section and there's a photo that is a ventral view of a female that shows a similar pattern to the one in your second photo.

We have tons of swallowtails here all summer---at least 6 or 8 different types, plus the females and males have different appearances, which makes it seem like there's even more different kinds but it is just the different sexes of each kind.

I love the swallowtails and this year they've laid plenty of eggs that have hatched out right in the garden, so I've been able to watch them "grow up" so to speak, which is fun.

Eastern Black Swallowtail

Thanks for this. I just found cats and thought they were Monarch but they are BST. Can't wait to see them turn into butterflies!!

It also strongly resembles a spicebush swallowtail, which I generally don't see here at our place. When a swallowtail that looks like a spicebush flies by, I always assume it is an eastern black swallowtail because that's what I see most often here.

Sori, I have had a garden full of swallowtail cats all spring and summer. I plant a lot of different plants for their larva to eat: several different kinds of parsley, fennel, bronze fennel and Florence fennel, and several kinds of dill. At this point the dill is all gone (it is cool-season) and so is the triple curled parsley. However the flat-leaf parsley remains, as do the various kinds of fennel. Usually in August I sow more dill seeds so the swallowtails will have dill in the autumn.

The biggest thing I do for the swallowtails is that I leave henbit in the yard and garden whenever and wherever it sprouts. Down here in southern OK, if it is a warm autumn and winter, we often have henbit sprout in November and in bloom by December. In a more normal weather year, it will sprout in January and be in bloom in February or occasionally not until early March. There's not a lot of flowers in bloom for the butterflies in November through February, so the henbit is one of the few food sources out there. It is fairly surprising how often I see butterflies out in the winter months...but only on nice, sunny and somewhat warm winter days.

There's tons of cats and butterflies of all kinds this year. It has been the best butterfly year in ages, but I only see a monarch once or twice a week. Normally I see more of them in October when they are migrating south. The monarch population is in huge trouble in this country and I've noticed I probably see only about 1/10th as many monarchs as I did 10 years ago. The reasons they are disappearing are complex, but I think that Bt-corn and a specific kind of chemical pesticide likely are playing a role in the disappearance of the monarch butterflies.

Dawn

I may never know exactly what that butterfly was. I was surprised it was still long enough for me to get the pictures I did. I notice they really go for the overgrown phlox under my big pines. Yesterday evening there were two of them. I'm not sure if they were battling for territory or feeling amorous, but they were rolling and flapping wings like crazy, even going through the branches of a crepe myrtle.

I'll have to remember about the henbit and will look for some dill seed next spring. I found some wild milkweed growing at the southeast corner of our yard. I'll have to tell Daryl to not weed eat them. I always mention monarch and hummingbird migration when I teach the Day of the Dead to my Spanish classes.

Thanks again, Dawn. You're my go-to gal for information!