Every so often I get an email from a student asking how they can cite this an article on this blog in a paper/lab report etc. I actually recommend not citing a blog in a scientific piece of work – citing websites is generally avoided as unlike more “solid” publications such as journals or books, websites can change or disappear. The work presented on blogs (unless taken from a paper) is extremely unlikely to have undergone peer review and you run a real risk that the information you want to use is just wrong. Even citing a Wikipedia article would be preferable to citing a blog, as at least that is a collaborative effort.
That said however, if you use pictures that are not your own, then you have to cite the source as best you can.
Citing a blog is essentially the same as citing a website. Ideally you want the URL, the title of the page, the date the page was created/made public, the date you accessed the page, and the author. All of this information is not always available, but you should use as much as you can. Bear in mind that less information makes a source appear less reliable.
Taking the Balancer Chromosomes article on this blog as an example:
Title: Balancer Chromosomes
Date page was created: 12/01/2009
Date accessed: 02/01/2014
Author: “Arrogant Scientist” or “Anonymous” (since Arrogant Scientist is clearly a pseudonym), or just leave blank.
How this bits of information are formatted in text or in the bibliography will depend on the citation style you are using.
If you have to cite an article with incomplete information, remember that it’s not your fault that the information is missing. Provide as much information as you can.