 The writing staff felt that " Zero Sum " was a logical place to bring back the bees that were used in the season premiere , " Herrenvolk " , feeling it was important to not have something paranormal happen to Skinner in this episode considering that had been done in the previous season . Live bees were used for filming , but showed up poorly in the footage ; visual effects technician Laurie Kallsen @-@ George then spent nine days digitally enhancing the footage to improve upon this . The virus @-@ carrying bees would later form a central plot point in the series ' 1998 feature film adaptation . 
