In the Mishna, Shabbat 1:3, it states (amongst other things) that one should not delouse one's garments by candlelight on Shabbat (ולא יפלה את כליו... לאור הנר). The following mishna, however, states that eighteen enactments were made on the day that representatives of the school of Shammai outnumbered the representatives of the school of Hillel, and the gemara interprets this particular ruling from Shabbat 1:3 as being amongst those eighteen.
Am I to understand, therefore, that the school of Hillel previously permitted delousing on Shabbat? It strikes me that such an activity would be a toldah of borer or gozez, or even hatzad tzvi. I presume that I must be misreading something, but am not sure what. Any advice would be appreciated.