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Mind-Controlling Wasps and Zombie Spiders

Article #3 • Written by Alan Bellows

In the forests of Costa Rica, there lurks a sinister variety of wasp, bent on hijacking the minds of hapless spiders for its own ends. Left unmolested, a variety of orb spider known as Plesiometa argyra spends every day of its life carefully reconstructing its perfectly round web, and feasting on the insects unfortunate enough to become snagged upon it. But should one of these spiders fall victim to this as-yet-unnamed species of wasp, the spider is stripped of its free will, and made to spend the last evening of its existence building a protective shelter for the larvae that infect it.

It is a true example of mind control in nature, and though scientists are well aware of the method of infection, they are uncertain exactly how the mind control is accomplished. When a wasp successfully attacks a host spider, the spider is temporarily paralyzed as the wasp lays eggs on the tip of the spider's abdomen. Once the wasp departs, the spider regains its ability to move, and it continues its daily web construction for the next two weeks as though nothing has changed. Meanwhile, the wasp's growing larvae cling to the spider's belly and feed on its juices through a number of small punctures.

On the night before the parasites kill their host, events take a bizarre turn. Through some unknown mechanism, the larvae compel their host spider to build a web that is very different from that it has always constructed before. Instead of a flat, round web, the spider builds a stout, reinforced platform which is much smaller. Once the new web is complete, the larvae kill their host, and cocoon themselves on the structure. It is ideal for the task, being resistant to wind and rain, and safe from the ants that inhabit the forest floor.

This behavior was first observed by Dr. William G. Eberhard at the university of Costa Rica. His observations have led him to believe that the mind control is most likely accomplished through a fast-acting chemical secreted by the larvae, but what that chemical is-- and how it works-- is a mystery. What he has found is that the spider's usual five-step web building process is reduced to two when held captive by these larvae, resulting in the alternate design; and he has also discovered that if he removes the larvae on the last day, just before the spider is killed, the spider will often recover after a few days of spinning the abnormal web.

It is true that many parasites are able to shape their host's behavior subtly, but never before has science observed a parasite that can manipulate its host in such a detailed, specific way. As evidenced by this finding, biology certainly has many fascinating secrets yet to be discovered.

Article written by Alan Bellows, published on 07 September 2005. Alan is the founder/designer/head writer/managing editor of Damn Interesting.

Article design and artwork by Alan Bellows.

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Posted 08 September 2005 at 01:14 am

Can you imagine all the implications if the environment/substance that caused mind control was discovered and isolated. The hostile applications alone are staggering.

Thanks for an informative piece.

Posted 08 September 2005 at 06:33 am

Yes, but it if it required that they put wasp larva in my belly button, I am sure it could be avoided.

Abu Ibrahim
Posted 21 December 2005 at 03:09 pm

This is a website that contains dozens of these amazing animal behaviours.
Although the site may be intended for a younger audience, you can still get a more scientific descriptions of these behaviours by googling the corresponding animals name.
As an example from the above site, there is a wasp called Ampulex compressa that injects venom into cockraches in order to guide the mind-controlled cockroach into the dining rtoom of the wasp's nest.

Abu Ibrahim
Posted 21 December 2005 at 03:10 pm

A scientific reference to my above post:

Fouad K, Liberstat F, and Rathmayer W (1996) Neuromodulation of the escape behavior of the cockroach Periplaneta americana by the venom of the parasitic wasp Ampulex compressa. J Comp Physiol A 178: 91-100.

Posted 15 July 2006 at 12:34 pm

I'm thinking I could use this to get my last employer to stop laying off good employees and spin a web to protect new ones... if not for the eating him part.

Posted 17 August 2006 at 08:12 am

Probably one of the most interesting articles I have read yet. Maybe the spider isnt just a host. Maybe the spider is a martyr or the Larvae Cause! Some sort of Arab spider perhaps.

Posted 14 February 2007 at 08:29 pm

Abu Ibrahim said: "

Interesting, this creature also seems to invoke some maternal mind control, from the parastite section of the site:

---Body Snatcher---

Sacculina, a type of barnacle, begins its life in the ocean as a free-swimming larva. When the female locates a crab, however, she actually discards most of her own body, leaving a gelatinous blob that enters the crab and begins to grow. It sprouts rootlike tendrils which spread through the crab like a plant, even wrapping around its eyes. Eventually it forms a small hole on the crab's back, through which male Sacculina can enter and permanently join the female. The crab stops growing and stops mating, devoting all of its energy into caring for the parasite's millions of eggs and larvae as if they were its own. Male crab hosts are altered by the parasite to think and act like females, even changing physically to better carry the barnacle's young.

Posted 01 September 2007 at 11:31 am


Posted 11 October 2007 at 01:00 pm

What a coincedence! The name of my ex-wife is Sacculina too!

Posted 30 November 2007 at 03:50 pm

Others mind-controlling species exists, or at least one: the "petite douve du foie" which in English seems to be the "lancet liver fluke" ( It's lifecycle includes controlling ants' mind in orther to be eaten by sheeps.

Posted 29 June 2008 at 10:41 pm

Enter your reply text here. OK

This will all be understood someday. We humans don't know squat about the universe or our earth. Good to be living today rather than in 1000 A.D.

Posted 04 February 2009 at 05:44 pm

I have to do it. :D

Religious perspective -
This is evidence of God showing his handiwork. A species that exists by such simple and elegant means. How could such chemicals cause the spider to build such a web and then encase itself ready to be eaten! This is not something it ever does on its is clearly very deftly being controlled by the tiny wasp larvae (who, one could draw the conclusion, cannot possibly be intelligent enough to be aware of what it is doing to its host). Clearly this could not possibly have "evolved" to be this must have been very clearly designed to function as such.

Scientific viewpoint:
Despite the religious nut's Point of View, the probability of this occuring has the same probability as any successful genetic mutation. Clearly the probability, despite the numerical odds against is 1. It is there, therefore it must have evolved to this stage as there is no other observable model to explain this. Surely there will be a similar species who almost has this same genetic makeup showing a step closer to another related species and hence we see the evidence of slight changes over time resulting in this phenominal specimen.
Fast forward 15 years. Science has discovered how the chemical signals work and have successfully cause a sheep to spin a web of wool and let itself be eaten by a pack of moths. Now, because science can observe and explain how something works, it MUST mean that there is no God behind it...yup!


Sorry, I had to.

Posted 08 July 2009 at 05:03 pm

another theory.
bugs and animals can actually speak to each other and the wasp was blackmailing the spider, using it's bellybutton as hostage actually never planning on letting it live.

reverie in the theatre of her mind

Posted 16 March 2010 at 02:41 am

The spiders are not actually controlled by the larvae, they are driven insane by the constant "DADDEEEE, MOMMMYY" the larvae yell and so it builds a weird web due to lack of concentration and eventually dies from MCOA syndrome. (Many Children on Abdomen)

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