Even though we all call them “blogs,” the technical name of this type of website is “web log,” and so that is what APA style uses.
Author Lastname. (Year, Month day). Title of Post [Web log post]. Retrieved from URL
If the author’s full name is available, use that in the citation. If only a screen name is available, use the screen name in the ‘author name’ position:
Kaufman, S. B. (2013, September 6). The real neuroscience of creativity [Web log post]. Retrieved from http://www.huffingtonpost.com/scott-barry-kaufman/the-real-neuroscience-of_b_3870582.html
Shortfinals. (2013, September 6). Bateman's - a national treasure [Web log post]. Retrieved from http://www.dailykos.com/story/2013/09/06/1236098/-Bateman-s-a-national-treasure