One of our readers wrote to us recently explaining that her cat found a worm in the corner of her living room, near the door that opens up onto the outdoor deck. The creature was black, hard, thin, and wiggling around a lot. She said that she had never seen anything like it before, so she picked it up and put it in a jar. After putting the wiggling worm in the jar, she noticed a dead cricket nearby. She also recalled that it had rained the previous night. Based on all these clues, our reader believes the black creature was a horsehair worm. Do we agree with our reader about this mysterious black worm?

We do! We are confident that this is a horsehair worm. During their larval stage, horsehair worms are parasitic towards arthropods, like beetles and cockroaches (and crickets!) They infect a host, and then eject themselves from the host when they sense they are near a body of water. In this situation, the horsehair worm likely infected the cricket that our reader noticed. When it was raining the night before she discovered it, the horsehair worm probably sensed the moisture and ejected itself from the cricket, killing the host in the process.

To wrap up, a reader described to us a series of events that occurred in her home. One night, it rained. The next day, she found a thin black worm in her home. Next to the worm she noticed a dead cricket.  Based off of these events, our reader guessed that the black creature was a horsehair worm. Hats off to our reader for solving this mystery! We too believe that she found a horsehair worm in her living room, the night after a rain storm.