What's That Bug? does not endorse extermination

spider with HUGE “parasite” (worm)
Hi. I sent an email several weeks ago (4-8 weeks) re: a spider with parasite. At the time, I was having problems with my internet service….so, I want to resend the email just in case you never received the original. Thanks for your advice/information about “my parasite problem”. July 2007-I saw what I thought was a fire ant in my basement living area (we do have problems with fire ants) because its abdomen was so large. I tried to catch the ant, but it was too fast. It jumped out of my bug catcher as quickly as I got it in. To say the least, he died. It scared me to death when he jumped out…..I thought he was going to sting me. I reacted……but anyways…….As I was doing research (to see if this large red ant was a fire ant), I noticed its intestines MOVED! After a couple of minutes, I realized that this was not the ant’s intestines…….it was a “worm” (parasite)!!! Sorry-no pictures that day! 2 weeks later, I was sitting in the floor in my living area of my basement. Low and behold, I seen a “worm” stuck to the bottom of my entertainment center with a dead ant next to it (I included pictures). I could see where the parasite had “busted” out of the ant’s abdomen. The “worm” was dead (dried up-guess it didn’t find a host in time).Attached is 2 pictures The last straw…….about 2 months ago, a huge Wolf spider ran towards my living area in my basement. I sprayed it with bug spray, and almost immediately, I saw a big “worm” bust out of the spider’s abdomen and begin to wriggle around looking for a host. I took many pictures and even a video (will try to send if I can figure out how to make smaller). 4 pictures are attached My concern is this……are we being attacked by parasites? I have 2 small children (ages 2 & 5) that both suck their thumbs. Do we have a parasite problem that needs to be dealt with? Is this common to see these parasites? Are they any harm to humans? Thanks so much for your help!!!!
Monica Lain
Nashville, Tennessee

Hi Monica,
We found a website entitled The Worm, the Spider and the Coffee Cup that discusses the Mermithid Worm as an internal parasite of spiders. Here is a quote from the site: “Mermithid worms are internal parasites whose infective larvae enter spiders directly or via ingested food. Once inside the spider, the tiny worm obtains nourishment from it’s hosts body fluids, digestive glands, gonads (‘parasitic castration’) and muscles. As a consequence the spider becomes progressively more debilitated, but doesn’t actually die. This is because the spider’s vital organs usually remain intact, even though all of the abdomen, and occasionally part of the cephalothorax, may be filled with worm coils. Eventually in a scene reminiscent of the movie “Alien”, the gorged worm bursts out of the body of the debilitated spider, which finally dies after this macabre event. Before it dies, however the spider often has to perform one more task for it’s deadly parasite. In some mermithids, the final free-living stage of the worm is aquatic, so that it is advantageous for the worm if its emergence can take place near a water body – a pond, a creek or puddle. To increase this likelihood, such worms seem able to induce their hapless hosts to seek water, spiders sometimes actually walking into the water before the worm emerges. This behavior may result from thirst-induced activity as the worm consumes the spider’s body fluids. Whatever the reason, there is no doubt that the spider’s water seeking behavior helps to ensure the parasite’s survival and propagation.” We also located a technical paper online. Nothing indicates the parasites are interested in your children.

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2 Responses to Mermithid Worm parasitizes spider

  1. [...] Are they any harm to humans? Thanks so much for your help!!!! Monica Lain Nashville, Tennessee Mermithid Worm parasitizes spider | What's That Bug? [...]

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