In a search for sandfly breeding sites in the Cévennes, France, six larvae of Phlebotomus ariasi were found in rotted manure in a cellar housing goats, and six adult flies of the same species were collected from emergence traps, one in the same cellar and five on a disused refuse dump. No sandflies were found emerging from holes of long-tailed field mice (Apodemus spp.) and no sandfly larvae were extracted from 77 kg (dry weight) and 130 kg (undried weight) of samples of soil or litter from different places. Total catches and the proportions of male flies in CDC miniature light traps were much higher in peridomestic than silvatic stations. About 15% of males caught in 3 peridomestic stations had unrotated genitalia. It is concluded that the larval breeding sites of P. ariasi are probably peridomestic and have a high content of organic matter. Observations on colonized P. ariasi show that, although immature stages of this fly need moisture, their requirements are comparatively low. It is suggested that female P. ariasi choose oviposition sites by sensing the presence of immature stages already in an optimal place.