Aphids Succumb to Low Temperature

At what low temperature will aphids succumb? I have an inactive greenhouse during the winter months with weeds from last summer that grew up between the crushed rock floor and were infested with aphids before I realized it. I was hoping that cold winter temps here in Maine would kill whatever live aphids or eggs remain. What do you advise?

The adult aphids will certainly succumb, but their eggs will not. In the spring I would advise you to either spray repeatedly with pyrethrum soap spray (available from Richters) to kill the hatching aphids as they emerge and buy some ladybugs to finish the job in June.