Franciscus Loos, a son of Johann Georg Loos & Maria Elisabetha Wild, was baptized on 27 January 1737 in the Catholic Church of St. Simon & Judas Thaddäus in Weidenthal, 19 kilometers west of Bad Dürkheim, in what today is the German State of Rheinland-Palatinate.
Franciscus and his wife Anna Elisabetha (surname unknown) immigrated to Russia, arriving in the Volga German colony of Schuck on 1 May 1767. They are recorded there on the 1767 Census in Household No. 31.
In 1791, Franz Loos and his family moved to the Volga German colony of Volmer where they are recorded on the 1798 Census in Household No. Vm15 along with his son in Household No. Vm22.
Mai, Brent Alan. 1798 Census of the German Colonies along the Volga: Economy, Population, and Agriculture (Lincoln, NE: American Historical Society of Germans from Russia, 1999).
Parish records of Weidenthal (LDS Film No. 367603).
Pleve, Igor. Einwanderung in das Wolgagebiet, 1764-1767 Band 4 (Göttingen: Nordost-Institut, 2008): 116-117.