Experimental infection with Quaranfil (QRF) virus does not inhibit the development of Argas (Persicargas) arboreus or the related species A. (P.) persicus. Intake of a QRF virus-infected blood meal reduced the reproduction rate (number of larvae per female) in A. persicus but not in A. arboreus. Subsequent feeding on uninfected chicks in both species restored the reproduction rate to normal. Development of both species during wintertime almost stopped under simulated outdoor climatic conditions whether the ticks were infected or not. In A. arboreus adults and nymphs the virus was maintained throughout winter under constantly controlled conditions regulated to 30oC, 75 % RH, and 24 hr. photoperiod, or simulated outdoor climatic conditions. Two months after infection, QRF virus was recovered from A. arboreus regardless of temperature or humidity. Five months after infection, QRF virus was recovered under regulated climatic conditions from males and females; nymphs were not tested. Under simulated outdoor climatic conditions, the virus::ould be recovered from females and nymphs but not from males. Virus was not recovered during winter months from A. persicus held under simulated outdoor conditions either 2 or 5 months after infection. From those held under regulated climatic conditions, QRF virus was recovered 2 months after infection from males and females. Five months after infection, it was recovered only from males. It is concluded that QRF virus can survive inside infected A. arboreus ticks all winter regardless of atmospheric conditions. The virus is occasionally maintained by A. persicus ticks if protected from unfavourable conditions of wintertime in Egypt.