Last week I was pulling some of my sweaters out of storage, because it is getting into full-on sweater weather. I was trying one on, not a care in the world, when my partner's mother pointed out a hole.
Surely it must have gotten caught in the zipper of the suitcase. Not a problem, I can mend it, it's fine. I went home, taking the case with me. But when I took out the other items, I found more holes, and they were bordered in these curious sandy gray deposits...
All in all, four articles had gotten nibbled, plus three big bags of fleece. Everything with evidence of moths went into the freezer for 3 days, then out to thaw, then back into the freezer again. The first freeze kills all the larvae and adults, the thaw allows any remaining eggs to hatch, and the second freeze kills whatever has hatched.
The fleeces got inspected, with any particularly nasty bits thrown out, and then washed. These were all unwashed fleeces - moths love dirt and sweat. I've learned my lesson.
I've darned stuff before, mostly the soles and heels of socks. In the past I've almost always used the usual darning stitch, which creates a woven patch. But the front of a sweater is more visible than the foot of a sock - I didn't want a conspicuous patch on the fabric, I just wanted the hole to seamlessly fade away.