Did extreme cold temperatures in Oklahoma affect stored grain insects?

During the middle of February 2021, Oklahoma experienced brutally cold temperatures.  The statewide average temperature on Feb. 15 was -18.2 C, the single coldest day statewide since 1915.  Feb. 15-16 and Feb. 14-16 also set records as the coldest 2-day and 3-day periods at -17.8 and -16.6 C, respectively.  Were those temperatures low enough for a prolonged period to kill insect pests in stored grain?  Unfortunately, the answer is no.  Large quantities of mainly hard red winter wheat are stored in steel bins, concrete silos, and flat storages across Oklahoma.  Some of these storage units hold 250,000 bushels of grain or more and can be over 75 feet in diameter.  Grain is a poor conductor of heat and when the surrounding temperature lowers, heat from a mass of grain is slowly lost to the surrounding air.  Grain has an insulation value of about R=1 per inch, so large masses of grain are well insulated, and those cold temperatures never reach the center of the grain mass.  Also, stored grain insects will tend to migrate to warmer regions in a grain mass and avoid colder areas.  Therefore, insect pests that infest stored grain have a protective advantage.