Spinochordodes tellinii is a parasitic nematomorph hairworm whose larvae develop in grasshoppers and crickets.

This parasite is able to influence its host's behavior: once the parasite is grown, it causes its grasshopper host to jump into water, where the grasshopper will likely drown.

The parasite then leaves its host; the adult worm lives and reproduces in water.

The precise molecular mechanism underlying the modification of the host's behaviour is not yet known.

Furthermore, it appears that the parasite produces proteins from the Wnt family that act directly on the development of the central nervous system and are similar to proteins known from other insects, suggesting an instance of molecular mimicry.