StackTrace

The first example uses:

Console.WriteLine(ex);

which is the overload of Console.WriteLine which takes an object parameter.

You may recall from a previous thread that the ToString() method is implicitly called on the object passed in and, in the case of the Exception class, this (by default) not only displays the stack trace but some other info besides. For more detail see:

http://msdn.microsoft.com/en-us/library/system.exception.tostring.aspx

So the answer to your question is that you don't necessarily need to use ex.StackTrace to determine the location of  the exception - you can use ex.ToString() as well.