I had read that ducks love watermelon rind so I had been putting some out for the ducks and other wildlife.
The other day I noticed about 4 butterflies on the old rind I am guessing they are drinking the juice.
We have had some watermelons we picked that looked good but they were not very sweet. Instead of just throwing them away we share with the wildlife.
Give it a try and see if you can get a few butterflies feeding on your watermelon.