I was asking you how the beetle related to the other parts of the dream so that the details about the beetle might come back to you more clearly – the details of its colouring,any special markings, how it moved, what kind of sounds it made, etc. Since the dream beetle came back to you after you saw the real beetle, it’s possible that you changed your memory of the dream beetle to make it seem closer to the beetle on your door because you wanted the beetle on your door to have a special significance. So you might have forgotten the things about the dream beetle that made it different than the real beetle, or you may have added some things to your memory of the dream beetle to make them more alike.
I’m also curious where you live that you have not seen a beetle in a long time.
It would also help if you could post the photo so other people could see if the beetle matches your description of the dream scarab in your original post or if they could see if they can interpret what the "weird blackness" is.
What did the business card say?
Whatever the reason that you saw the beetle on your door, the fact that it made you focus on the scarab beetle in your dream means that the beetle was probably an important part of your dream. A
scarab in a dream can mean that you are thinking about your own mortality. It can also stand for your ability to survive as things change around you.