You’d be right to think that palolo worms appear mostly on low outgoing tides–though they also appear more often on low incoming tides in some locations. You’d also be excused for thinking that it only happens on the full moon, though they appear (in somewhat lesser numbers) on the new moon as well. You’d be mostly correct to assume that worm hatches happen in the late afternoon and early evening, and on calm days on the ocean side of the Keys; but worm hatches can happen in the middle of the day, and in the backcountry and on any hard coral bottom, even in a stiff wind. Most palolo worms have greenish “heads” and pinkish red “tails,” but you’ll occasionally see worms with almost white heads or dark red tails.
The most common misconception may be that worm hatches happen only on one or two nights in a given area. In fact, they can continue for five or six nights in one spot, changing their location as the tidal flow shifts around a set of flats. For example, in the area I’ve been fishing them this week, they first appeared in two-foot seas at the end of a channel, then moved outside the channel on the next night, then further up the channel on consecutive nights as the wind lay down. The only common ingredient was a bottom covered with loggerhead sponges, sea fans, and hard white limestone.
If you’re lucky enough to see one big worm hatch in a lifetime, you won’t forget it. Treating them as events that you can fish for up to a week at a time greatly extends the excitement. And don’t get up before dawn, fish all day in the heat, and expect to have the energy to find worms at dusk. Finding this macro event with a full battery is a whole lot more fun and worth your full attention, even if the fish aren’t constantly eating your flies. Being surrounded by the slurp-gurgle-slurp of tarpon completely abandoned to their task is worth almost any amount of effort.