Daiwa Worm Threader - Blue
The Daiwa Worm Threader is an ingenious tool that makes it much easier to thread a worm onto a hook. There are several ways to put a worm on a hook. There are a few YouTube videos showing you how to do it but they use a nightcrawler.
Throughout the worm fishing pages on TenkaraBum, I have urged people to not use nightcrawlers when fishing for trout - particularly if they do not intend to keep every fish the catch, no matter what size. The problem with nightcrawlers is that they are too large. A night crawler, or even half a nightcrawler, is too large for all but the largest trout to get the whole thing into its mouth all at once.
If the part of the crawler that has the hook is outside of the mouth, you will feel the take, but you when you try to set the hook there's no fish there. You've just pulled the crawler out of its mouth. If you wait "to make sure he's got it," you can be sure he's got it down his throat. That's what was taught when I was little, when we kept every trout we caught.
There's a better way. Just use a smaller worm.