The San Juan worm has been a go to in my warm water fly case. It mimics the natural red worm that play a part in the local fish diet throughout most of the season. Bluegill/sunfish go crazy over it, especially after I started adding wire weighting or gold bead to it. The sinking action allows for you to sink it delicately in front of a rock cropping to grab panfish, rock bass, or smallmouth bass.
One thing I forgot to add to the clip above is melting the ends with a lighter, it adds the natural rounded ends to make the worm more realistic.
Size 14 nymph hook
Black thread 140 (can also match the color of the worm with thread to blend more)