What Is Phoresy?

Phoresy is a type of symbiosis in which one organism "uses" another for transportation. This example, is a rather disgusting one, in which a parasitic fly (the Torsalo Fly) utilizes other parasites (in this case a mosquito) to adhere its eggs to. Upon contacting its warm blooded meal, the mosquito, concerned only about its own well being, provides the attached parasites eggs to begin development.

This would appear as a highly co-evolved parasitism in that the vector is actually another parasite. The bot fly itself is a parasite during the larval stage of its life cycle. During the adult stage, however, it relies on another organism to fulfill its work in distributing its offspring.

More detail on this rather ugly human parasite is here, to which we credit the image above.