The Spinochordodes tellinii is a nematomorph hairworm. Its parasitic larvae develop in orthoptera insects such as grasshoppers and crickets. The parasite is dangerous because it affects the central nervous system of its host.
How does the parasite work its damage? The adult worm influences the host’s behaviour. For example, the Spinochordodes tellinii may influence a grasshopper to jump into water and cause the insect’s death. An uninfected grasshopper wouldn’t do that. After the host is dead, the parasite reproduces in the water.
An adult Spinochordodes tellinii worm may become three or four times longer than its host. In 2005 a study team found out that infected grasshoppers produce some kind of protein in their brains, different from the one in the uninfected insect. This kind of protein might be the cause of the host’s strange behaviour, because it could be affecting the host’s nervous system.
The Spinochordodes tellinii isn’t dangerous to humans because such types of hairworms parasite only on invertebrates and orthoptera insects.