Best way to catch tarantulas and scorpions.

There is another way to catch one, but it's much riskier. Let the tarantula or scorpion chase after you and swing your net with the right timing. This is how I caught 2 scorpions.
You should always keep your net out. Don't wait till you see one to whip out your net. Cause it'll attack, those weird things...and do what the person above my post said. *whispers* it really does work. :3
I caught my tarantula and scorpion by using the cliff-method, which I think is the easiest way to catch them.
1. Find one. Take out net. RUN LIEK HAIL. Snatch it up. Done.

2. Walk around with net until you find one.

3. Cliff-method.
Take your net out prior to searching for one, so that when you find it, it won't chase you. Just go up slowly and catch it.

That method seems to be the easiest in my opinion.

Don't run around though. You'll scare it and it will start running around like a banshee and be harder to catch.