They couldn't have! Amazing antifreeze lets them survive minus 37 degrees, not possible to have developed this trait in stages...
"Frozen Alive? All by Design, by Jonathan C. O'Quinn, D.P.M, M.S. (Abbreviated version)
(This article digest is by Marko Malyj, of the article published in Creation Matters, Volume 15, Number 4, July/August 2010, a publication of the Creation Research Society, to appear 2011 at http://www.creationresearch.org/creation_matters/pdf/2010/CM15%2004%20low%20res.pdf).
E. Kristiansen, N. G. Li, A. I. Averensky, A. E. Laugsand and K. E. Zachariassen, 2009. The Siberian timberman Acanthocinus aedilis: a freeze-tolerant beetle with low supercooling points. J. Comp. Physiol. B 179:563-68.