Well its past March 20th and spring is officially here. Temperatures are beginning their slow climb and we are seeing more days in the 50's when the bees can get out and fly. But here in Wisconsin we still can get occassional bouts of snow in April and frosts well into May.
Its also about time to think about removing winter wrapping from your beehives. At this point the wrap is probably preventing the sun's rays and warmer outside temperatures from warming the hive. Also as previously discussed wrapping has no real measurable effect on hive survival unless your hives are fully exposed to the prevailing winter winds.
In my apiary I have lost 3 wrapped hives (15%) and 3 unwrapped hives (also 15%). So for the 3rd year running I don't have evidence that hive wrapping has either a positive or negative impact. NOTE: All of my hives are protected from the previaling NW winter winds.
On those 50+ degree F days it might be a good idea to make a quick snap inspection of your survivor hives. Don't do anything other than removing the outer and inner covers for a few seconds to see if you can see some capped or open honey. If not, you need to feed. It would be a shame to lose a hive to starvation after making it all the way through the winter. The trees and dandelions are not producing pollen or nectar yet.