This Roman Catholic Cemetery was established on June 20, 1855. It was the original St. Patrick's Cemetery in Flos Township. It was referred to as the Flos Cemetery or the Apto Cemetery in the Catholic burial records. It lies on Lot 2, Concession 1 of Flos Township. Prior to becoming a home for the original St. Patrick's Catholic Church and the Apto Cemetery, this land was the former farm of Henry McAvoy who is now interred here.

There is a marker for Ann nee Lunn Moran showing a death date of 1847. It is believed that this is a cenotaph. Mrs. Moran died of ship fever, according to her son's obituary, and there is no evidence that she ever lived in Flos Township. Her family is buried here and it is believed she was memorialized on the marker.

The first known burial was John O'Neill, who died just 9 days after the start of the cemetery.
The Catholic Church decided to close the burials in this cemetery and encouraged parishioners to use the new cemetery, St. Patrick's Cemetery in Phelpston, also located in Flos Township. Some transferred their loved ones from this cemetery to the new St. Patrick's Cemetery when it opened in 1903. While burials closed for Apto Cemetery, permission was granted for James Hayes who died in 1919 and his daughter, Margaret who died in 1941 to be interred with other family members in this cemetery.

The cemetery was largely abandoned by the Catholic Church once the new St. Patrick's Cemetery in Phelpston opened in 1903 and over the years the stones in the Apto Cemetery became broken and damaged. Flos Township took over maintenance and in 1998 what stones could be salvaged where made into a cairn on the site. Three of the family markers remain in their original position. The family markers found at each end of the cairn (the Hayes and the Savage markers) and the marker, imported from Ireland, for McMahon found in the middle of the cairn remain in their original position.

The burial records from 1855 to 1863 have survived and can be found on Ancestry and FamilySearch. Lost/destroyed or never kept are the records of burials from Aug. 13, 1863 to Dec. 12, 1882 and the records from Dec. 13, 1882 to Dec. 31, 1910 can be found on Ancestry and FamilySearch. The two burial records after 1910 can be viewed, by appointment, on microfilm at the Archives of the Roman Catholic Archdiocese of Toronto.