Come Autumn, it’s time to check on the bees and make sure they’re ready for the forthcoming winter - which means being sure they have plenty of stores!
The traditional way to tell the weight of a hives was to ‘heft’ it - lift one side and judge how much it weighs - an easy lift and they’re low on stores - a hard lift, where you have to bend your knees, and they’re all set! However, this is not an easy test to explain to new beekeepers, and it’s probably a good idea to lay out exactly what is meant by ‘enough stores’.
Bees in the UK generally need around 18kg (40lbs) of stores to see them through the winter - they might need more in a hard winter, or get away with less in a mild one, but this is a good target to aim for.
Since bees tend to be fairly symmetrical when they lay down stores, you can usually weigh one side, and then double this to get the total weight. (Or weigh both sides and add them together, if you’re being picky). I tend to lift from the back, since hives are usually more symmetrical front-to-back than side-to-side.
But you also need to know the net weight of the hive equipment, to subtract from this gross weight and let you know the total amount of stores. I’ve made some measurements of empty equipment at the apiary, and can provide the following approximate weights for the main hive parts:
- OMF Floor: 2kg
- National Brood Box: 3.5kg
- 11 Hoffman BS Frames (undrawn): 3kg
- Coverboard: 1kg
- Roof (shallow or deep): 3.5/4.5kg
So a single national is 13 or 14kg, while a double is 19.5 or 20.5kg (roof-=depending).
So, today I weighed 2 of my hives to try out this process. My guess was that hive 1 was ok, while hive 2 was a bit light, by hefting alone.
Double brood, shallow roof - 38kg gross. 38 - 19.5 = 18.5kg stores.
Single brood, deep roof - 30kg gross. 30 - 14 = 16kg stores.
This means that hive 1 is just over the minimum, while hive 2 is well under. As a result, I will be feeding hive 1 5L 2:1 syrup (approx 5kg sugar) and hive 2 8L 2:1 syrup (approx 8kg sugar) to get them both over 22kg of stores.