In the studies on the ecology of the parasite fauna of free living small mammals in Formentera (Balearic Islands) notable differences as regards similar works in other islands or in the continent were found. The particular qualitative and quantitative composition of the ectofauna and endofauna can be explained by the special phisiography of the island and
the uncommon ecology of the definitive hosts (domination of the garden dormouse).
On the basis of these investigations and of the data of the short literature dealing with the topic «parasitology in isolated ecosystems», it can be deduced a number of advantages
and disadvantages offered by insular ecosystems in respect to parasitological research and finally the general interest of them