“Yesterday my kids caught a Hentz Orb-weaver in a small mason jar. I was going to set it free but I completely forgot about the spider and it was left in the sealed jar on my back porch and when I woke up I noticed the spider was dead but there was also a long skinny light brown worm like creature inside the jar next to the dead spider”, writes Kelsey in his submission regarding the worm pictured below. “I’m completely baffled because this worm was not in the jar last night and the Mason jar has a sealed aluminum lid so I can’t imagine anything getting through that. How did the worm get in the jar? Is it some kind of parasitic worm? Can orb weaver spiders carry parasitic worms? I am a little freaked out and I really want to know how and why this is possible. Please help! Oh and the worm is very much alive by the way.”

To start with, we want to thank Kelsey for the excellent photos he sent (the best of which we include below), as well as the bountiful context. This story is fascinating, and we are happy to say that we have all the answers to Kelsey’s questions. As mysterious as this worm’s appearance seems, Kelsey guessed correctly: this is a parasite. Specifically, it is a horsehair worm. The important thing to note here is that this parasite does not purposefully infect humans. The only way to ‘contract’ a horsehair worms is to ingest it, and the most that will happen is that you A) Cough/throw it up, or B) Experience some stomach pains as it passes through your digestive tract. They will not give you any actual symptoms, as they are unable to take mammals as hosts.

Horsehair worms infect insects, arthropods, and yes, spiders. The explanation behind what has happened here is quite fascinating, though gruesome. Like most endoparasites (parasites that feed inside their hosts – as opposed to ectoparasites that feed on the outside, like leeches or fleas), horsehair worms mature inside the bodies of their hosts by feeding on the nutrients they consume. Once a horsehair worm has fully developed, it will burst forth from the host, killing it in the process. This can be quite messy sometimes: the host will literally explode. Sometimes it’s quite a clean endeavor like this one, where the spider is seemingly intact, but still very much dead.

In conclusion, this worm did not teleport into the jar to murder this spider, but was rather inside the spider the entire time and killed it by coming out – a rather macabre magic trick if you ask us. To repeat: horsehair worms are not dangerous to humans, and Kelsey needs not worry about himself or his children. We hope this helps, and we wish him and his children the very best.

Summary

Article Name

Skinny Light Brown Worm Appearing Next to Dead Spider is a Horsehair Worm

Description

"Yesterday my kids caught a Hentz Orb-weaver in a small mason jar. I was going to set it free but I completely forgot about the spider and it was left in the sealed jar on my back porch and when I woke up I noticed the spider was dead but there was also a long skinny light brown worm like creature inside the jar next to the dead spider", writes Kelsey in his submission regarding the worm pictured below. "I’m completely baffled because this worm was not in the jar last night and the Mason jar has a sealed aluminum lid so I can't imagine anything getting through that. How did the worm get in the jar? Is it some kind of parasitic worm? Can orb weaver spiders carry parasitic worms? I am a little freaked out and I really want to know how and why this is possible. Please help! Oh and the worm is very much alive by the way."

Author

Worm Researcher Anton