A lot of places I have been looking suggest 12c as the sweet spot for hibernating you ants with the highest range being from 15-18c depending of the source.
http://antfarm.yuku....ng#.V_fJnPkrLIV - Different forum with a post involving ant keeping. TLDR: Keep temps above freezing but generally below 60f.
http://www.formicult...-for-beginners/ - A post by our own Crystals. TLDR: 5-12c
https://www.youtube....h?v=BDgleH51Kd4 - Older antscanada video covering hibernation. TLDR: No specific temps. Keep cold but not outside temps. Duration is about end of Oct, early Nov until march. For Toronto, Canada.
https://youtu.be/FqAYguIvPqc?t=2m29s - Video from antbatman. TLDR: 2-10c.
Many more sources available. This is just where I decided to stop.
Current Colony:
4x Camponotus (hyatti?)
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Harmony with land is like harmony with a friend; you cannot cherish his right hand and chop off his left.
-Aldo Leopold