We believe the small black organisms our reader found in her pond are either leeches or black fly larvae. Both are similar in appearance, though leeches are slightly bigger, and both are commonly found in ponds. Neither species are considered invasive and neither should damage her pond or cause any problems with the fish!

We received an interesting and fairly perplexing question from a reader yesterday about “a bunch of small white worms or larva.” (It should be “larvae,” with that bizarre Latinate ending to indicate plurality, for the record.) The worms or larvae were found in a pond that is used by cattle at a dairy. The creatures in the pond are about an inch long and they have a tail that is about as long as the body. The reader sent a nice (if confusing) picture of the worms or larvae, which we have included below. What are these worms or larvae in the pond?

A little while ago we received a question from a reader about some worms she is finding in a pond. The pond worms are white and brown, although the proportion of each color varies from worm to worm; some worms are only slightly brown, with white serving as the worm’s main color, whereas others are almost entirely brown. (In any case, this is what we gathered. The email is a little hard to decipher; fractions like 3/4 are invoked to describe the worm’s colors, which is helpful, but it’s not always clear what color the fractions are referring to.) The reader also mentioned that the worms are small, in the 1/4 to 1/2 of an inch (6-12 mm) range. So, our reader is dealing with some small brown and white worms, and the question of course is: what are they?