I overwintered my nanners in a three season room in N. Il. using electric heaters ( Expensive ) not rec. Had two bouts with spider mites. 1 Ounce Fish Emulsion per gallon of water took care of them both times, not sure if it smothered them or they just couldn't stand the smell for two days, and ran off to freeze out side. I used a spray bottle and face mask, wife and kids complained but it dissipated after 2 or 3 days, no smell in the house, JUST DON"T OPEN THAT DOOR!!!!!!!! for a few of days.
