It is a way of calling insects sucking. They belong to the families Siphonaptera (fleas) and Aphidae (aphids). Popularly they are also called siphonaptera and aphids respectively. They are usually sucking parasites and usually feed on blood (hematophages) or plant fluids. In many cases they are vectors transmitting diseases caused by viruses. Their oral apparatus is transformed into a channel or tube that makes it easier for them to suck their food.
Person considered as a parasitic bug, which consumes other people's resources or that do not correspond to him. The folk etymology links "sucking" ("absorbing") with the suffix -ptero ("winged") which sounds like a bug like the mosquito (which is a diptera) or the flea (which is an apterous insect).
