I went through a lot of searches on euthanasia for small insects when my pet spider was struggling to get around and stopped eating.

Basically, all the methods are slow, painful and scary… Except for one. Crushing is near instant, faster than they can register pain, just a spider one moment and a smear the next. It’s probably the toughest way for you, but it’s the fastest, least painful, and least stressful way for them.