You won’t catch butterflies sitting at your desk. Look for them out and about. Take the net with you. They will flutter past as you drive, as you walk or cycle or buy groceries or tend a child with a grazed knee. Grab them swiftly and gently, and put them in a jar for later.
Next time you’re at the desk, take out the jar and let them flutter around you until they alight on the page and slowly arrange themselves in order. Now you can write them down.