Four bugs are located in the corners of a square, 10 inches on the side. They are arranged like this:

            A---B
            |   |
            D---C 

As the clock starts, A begins crawling directly toward B, which goes to C, C goes to D and D to A.

Each bug will home in exactly on its target, reguardless of the target's motion, so their paths will be curves spiraling toward the center of the square where they will meet.

What distance will each of the bugs have covered by then?