Regarding last week's question about leeches in northern California lakes, we got some additional interesting feedback. DFG environmental scientist Mary Meyer, who has extensively studied the Eagle Lake area in particular, confirms that Eagle Lake supports a variety of unique invertebrates, including freshwater hydra, freshwater sponges and abundant leech populations. "If you wade or stand around in the water, they may attach. If you swim around and don't stay still long, they tend to leave you alone," she says. Eagle Lake also has the parasite that causes swimmers' itch and can infest humans, particularly if you are standing or wading in the water.

Meyer also guesses that the wormlike creatures in Clear Creek were likely black fly larvae of the Family Simuliidae. Some folks call these black flies no-see-ums. The adult females are rather slow-moving and smaller than a house fly. They may bite humans and other mammals and those bites can be itchy for a day or two. The aquatic larvae are black and attach in masses to the surface of rocks in swift water, anchored by a silk thread. They are benign at this stage and often confused with leeches simply because they are small, black and wiggly.