Basically, it's believed that for the two days after Candlemass (i.e. yesterday and today), and for a week in November, the wolves are hungry, angry, and prone to attacking people and livestock. To ward off these attacks, certain kinds of domestic activities are prohibited. Iron and metal tools are compared to wolves' teeth, so any work in which the metaphoric teeth "bite" wool (playing the part of the threatened livestock) is believed to encourage an attack.
The exact work that's forbidden varies from region to region. In the place I grew up, you're not allowed to:
- Use scissors for any task, even ones that don't involve fabric;
- Card or comb wool;
- Use a needle.