Dr. Kassai Tibor szerk.: Parasitologia Hungarica 2. (Budapest, 1969)

I should like to put forward a most characteristic example (not contained in the Tables, because the case was studied after the period under investigation). In October, 1968, in the southern part of the country (Madaras) an ermine (Mustela erminea aestiva Kerr) made its subterranean quarters in a field much infested by gophers. We succeeded in shooting the animal. Fourteen of the fifteen flea specimens found on it proved to belong to the specific fleas of the gopher (

Citellophilus martinoi and Ctenophthalmus orientális

). This comparatively large number of individuals also indicates that the flea species mentioned do not attach themselves so much to their hosts as to the habitat of the nesting site. DUDICH (1939) has already remarked that one usually encounters difficulties when attempting to establish the biotopes of species. This statement is especially true of parasites and thus of fleas. What then, are the biotopes of fleas? Environment in the stricter or wider sense of the term? There are species which occur on animals living in pastures and agricultural areas of the plains, and ethers on forest mammals. Some are more frequent in arid, others in damper habitats. I failed to find any

.demonstrable connection between the plant cover, the forest stand,and the occurrence of flea species; - if the hosts are present, and their burrows and nests suitable for invasion by and reproduction of fleas, we might expect the appearance of certain species. Hence the biotope of flea species is not the wider but the more restricted habitat; the small area where they reproduce, lay their eggs, the larvae find their food, and the pupae transform into imagos. In the search for the biotope of the fleas we have thus arrived at the lairs of their hosts, be they subterranean burrows, holes, or nests constructed on the ground, on clumps of grass, shrubs, or trees. (Tne bizarre idea that the biotope of the flea species is the host itself should be rejected at once; this assumption may be justified only in some cases of endoparasitism.

) The biotopes mentioned above can be delineated rather satisfactorily and also assigned to the biocoenological horizons of the temperate regions es-