Spinochordodes tellinii

The nematomorph hairworm Spinochordodes tellinii is a parasitic worm whose larvae develop in Orthopteran insects. This parasite is unique in being able to influence its host's nervous system in a manner comparable to mind control. Shortly before it is ready to leave the host, the parasite causes the grasshopper host to jump into water, where the grasshopper will drown.

It is not known however whether the neuromodulatory process underlying the host's behaviour involves a manipulation of the nervous system or some other factor. Studies have indicated that grasshoppers which contain the parasite express, or create, different proteins in their brains than uninfected grasshoppers. Some of these proteins have been linked to neurotransmitter activity, others to geotactic activity, or the body's response to changes in gravity.