Seriously - What's going on?

I was outside weeding in the side yard this afternoon. Nora was with me. I'm minding my own business, pulling weeds, wishing I had watered the ground this morning so I could actually get the roots out and I hear a rustling. I look up, expecting to see Nora doing something near me. Nope. It was a snake slithering away from me with something in its mouth. I F.R.EAKED out! I yelled to Nora to get inside the fence and ran in there myself. The fence is only waist height so we stood on the other side and watched as it slithered to the opposite side of the air conditioner. I could see its tail and I threw a rock at it to see if it would move. Nope. So I carefully stepped outside of the gate and tip toed over to a better viewing area and saw that it was eating a frog. I had thoughts of sitting there watching it eat the frog, but I was a bit too panicked to do that - and Nora was inching her way out of the backyard, too, to see what was going on. As brilliant as I am, I realized that we could probably see it from the dining room window. Nora and I ran into the house and perched on the window sill and watched for 45 minutes as this thing inhaled the frog. I was fascinated. Nora - not so much:)

This is the snake eating the frog. You may have to click on the picture to get a closer view. The head and the frog blend in with the rocks.

Here is the snake after eating the frog. You can see a big bulge right after its head.

It was pretty fascinating to watch. The frog was still alive when we first got to the window. I didn't think the snake would be able to swallow the big, fat belly of the frog because the snakes head was so small, but obviously I don't know anything.

So I'm a bit worried about this snake business. First, I need to announce that I'm really sick of all of these animals coming to our house uninvited. Dog - okay. Fish - okay. Tadpoles - okay. Racoons - not so much. Snakes - definitely not so much. Second, I'm worried about letting the girls play outside. I don't know where this snake lives, don't know if it is poisonous (anyone I talk to says that we don't have poisonous snakes in Chicago, but this one was black with some red/orange on it - I thought red was a danger sign in nature). Even if it doesn't live in our backyard, it still traveled through the backyard to get to the side yard. What if it lives in the side yard? We have so many weeds that need to be pulled, now I can't do it. I don't think I can even walk through the grass on that side of the yard anymore (you know it will only be on THAT side of the yard, the other side of the yard is completely safe;). What if the girls are minding their own businesses and walk through some leaves that the snake is hiding in and it bites one of them?

We're having a barbecue on Memorial Day and I'm trying to get the backyard looking somewhat presentable. Oh and how about that? What if our new pet bites one of our guests? Oh I needed this situation like a hole in the head.