The underestimated spring risk: when cold, wet days eat into the feed stores

A brief look back: why weight monitoring matters so much in winter

In part 1 of our series on winter feeding we went through in detail how to bring your bee colonies safely through the cold months: from the right starting weight in autumn, through working out your own empty weight, to the critical thresholds and the right way to give emergency feed.

The most important points in brief:

• Individual reference values matter more than blanket table figures
• Early warning at 7-10 kg of weight lost from the starting weight (Dadant/Zander)
• Critical at 12-15 kg of weight lost
• In winter only feed candy or fondant, never liquid feed
• From January onwards, check weekly

If you have taken those basics to heart, your colonies will have come through the depth of winter well. But in late winter and early spring there is a situation that many beekeepers underestimate - and one that, paradoxically, affects precisely the strongest and most vigorous colonies.

The underestimated challenge: when the nectar dries up

Most beekeepers know the risk of winter starvation in January and February. But a second, equally important phase is often overlooked: the spring, and March and April in particular, when cold snaps or persistently wet weather stop the nectar coming in.

The deceptive calm after winter

In February and March the situation in your colonies changes fundamentally. The queen starts laying again, brood rearing picks up, and on the first warm days thousands of bees fly out. They bring in pollen and - if all goes well - the first nectar as well, from willows, crocuses and early fruit blossom.

This incoming nectar normally covers the enormous energy requirement of the expanding colonies. The winter reserves still seem to be sufficient, the scale may still show 8 or 10 kilograms of feed, and many beekeepers no longer weigh their colonies all that carefully at this stage. Winter is over, after all, is it not?

This is exactly where the danger lies in wait.

The scenario: a week of rain in March

Imagine the following. It is mid-March, your colonies have come out of the winter strong, brood rearing is in full swing. On the last sunny days you have seen the bees busily bringing in pollen. Everything seems to be going well.

Then the weather turns. A cold front brings days of rain, temperatures fall to 5 to 8 degrees, the wind whistles. Flying is out of the question.

What is happening in the hive?

The brood is there - thousands of larvae have to be fed. The nurse bees are working flat out to keep the brood warm and looked after. The heater bees hold the hive temperature at 35 degrees. All of that costs enormous amounts of energy.

But nothing is coming in. No nectar arrives, the bees cannot fly. The colony lives entirely off its reserves.

Consumption stays high, and nothing comes in to replace it.

Why it is the strong colonies that are affected

The paradox of this situation: it hits above all the strong, vigorous colonies with the most brood. Weaker colonies with less brood also use less feed. But a strong colony that is already tending several frames of brood in March cannot simply throttle back its feed consumption.

The figures at a glance

What is normal in the depth of winter - roughly 200 to 400 grams a week - accelerates markedly in spring:

A simple rule of thumb: colonies that are not raising brood use about 1 kg a month, colonies that are raising brood about 3 kg a month. In March, with brood rearing in full swing and in bad weather, consumption can be considerably higher still.

A strong colony with a large area of brood can use 1.5 to 2 kilograms of feed a week during a bad-weather spell in March or April - that is four to five times the winter consumption! In extreme cases, with very large colonies and persistent bad weather, even more.

A worked example: from plenty into crisis

Let us take a concrete example:

• 1 March: your colony still has 10 kg of feed in reserve. Everything seems fine.
• Week 1 (sunny): bees fly and bring in nectar. The net weight stays level or even rises slightly.
• Week 2 (rain, 6°C): no flying. Consumption: 1.5 kg. Feed left: 8.5 kg.
• Week 3 (more rain): consumption: 1.8 kg. Feed left: 6.7 kg.
• Week 4 (more rain): consumption: 2 kg. Feed left: 4.7 kg.
• Week 5: the shortage of feed becomes critical.

In three weeks of bad weather, a colony that appeared to be well supplied can end up in a critical situation. And bear in mind: in April, after a brief improvement, the next wet spell may follow - and then it carries on downhill from 4.7 kg.

The warning sign: accelerated weight loss in spring

In winter we learned that more than 400 grams of weight loss a week in December (or 800 grams in January/February) is a warning sign. In spring different rules apply, because the underlying consumption is considerably higher on account of the brood rearing.

New thresholds for March and April

Normal in spring:

• 0.7-1.2 kg of weight loss per week in changeable weather
• Gains in weight on individual good flying days (nectar!)
• Fluctuations in weight depending on the weather - the zigzag pattern is normal

Warning sign in spring:

• More than 1.5 kg of weight loss a week with no flying
• A continuous downward trend over several days with no recovery
• Less than 6 kg of feed left with bad weather forecast

Critical in spring:

• More than 2 kg of weight loss a week
• Less than 4 kg of feed left
• A bad-weather spell of more than 5 days forecast

The awkward thing about the weight curve in spring

Unlike in winter, where the weight curve shows a steady, predictable decline, the spring curve is a zigzag pattern:

• On good days the weight rises (nectar coming in)
• On rainy days the weight falls (consumption with nothing coming in)
• The brood rearing means fundamentally higher consumption

This pattern makes it harder to spot problems. A single day with a loss of weight is normal. But if you see nothing but losses over several days in a row, and the forecast promises no improvement, you have to act.

The false sense of security after a mild winter

The situation is particularly dangerous after a mild winter, when the colonies have come through well and still have a decent amount of feed. At this stage beekeepers often stop weighing regularly, because they think:

"There were still 12 kilograms in February, that will easily last until the fruit blossom."

But that sum does not add up when the spring is cold and wet. Colonies can run short of feed just a few weeks before the nectar flow begins.

The psychological factor

After a long winter, beekeepers are relieved when their colonies have survived. Attention turns to other things: getting the colonies out of winter, the first inspections, preparing frames. Weight monitoring slips into the background.

That is exactly what can lead to trouble.

What you need to watch in spring

1. Check more often, not less often

From mid-March onwards you should check the weight at least twice a week - not just once as in winter. Particularly before and during bad-weather spells:

• Before forecast rain: note down the weight
• During the bad-weather spell: check every 2-3 days
• After the bad-weather spell: take stock

2. Keep an eye on the weather forecast

In spring the weather forecast is your most important tool alongside the hive scale:

• Are several days of rain or temperatures below 10°C forecast?
• How much feed does your colony have left?
• Will the feed last through the whole bad-weather spell?

Rule of thumb: if more than a week of bad weather is forecast and there is less than 8 kg of feed left, you should feed preventively.

3. Have emergency feed to hand

In spring you should always have feed candy or fondant to hand. Do not go and get it once the problem is acute, but beforehand:

• 2-3 kg of feed candy per colony in reserve
• Stored in a dry, cool place
• Quickly available when needed

4. Act sooner than in winter

In winter, once the early warning threshold is reached, you still have one or two weeks to plan. Not in spring! If you see that:

• The weight is falling fast (>1.5 kg a week with no flying)
• Bad weather is forecast
• The feed left is dropping below 6 kg

...then feed immediately, not next week.

5. Watch the flying activity

In spring, flying activity is an important indicator:

• Bees flying and bringing in pollen: nectar is probably coming in too. Check the weight to confirm.
• Bees flying, but no pollen coming in: take care, they may not be finding anything.
• No flying at all: the colony is living off its reserves alone. Watch the weight closely.

Emergency feeding in spring: different from winter

In winter we established that it is feed candy or fondant only, never liquid feed. In spring, some of the rules are different.

Feed candy remains the safe choice

Feed candy works reliably in spring too:

• Can be given at any time
• No risk from condensation
• The bees take it as they need it

Liquid feed becomes possible again

From mid-March, once temperatures become more settled and no prolonged spells of frost are to be expected any more, you can give liquid feed again as well:

• Only at temperatures above 10°C
• No risk of frost in the next 3-4 days
• Smaller quantities (1-2 litres), so that it is taken down quickly

The advantage of liquid feed in spring: it stimulates brood rearing and is taken up faster than feed candy. With an acute shortage of feed, that can be decisive.

Which feed, and when?

The advantage of digital hive scales in spring

It is in spring in particular that the true value of a digital hive scale shows itself. You see:

• Daily changes in weight without driving out to the apiary
• Trends over several days - is the weight rising (something coming in) or falling (consumption only)?
• Automatic warnings when weight is lost quickly

Adjusting the warning levels for spring

If you use a digital hive scale with a warning function, you should adjust the warning levels from March onwards:

Winter setting (December-February):

• Warning at >0.4 kg lost per week (December) or >0.8 kg (January/February)
• Critical at less than 5 kg of feed left

Spring setting (March-April):

• Warning at >1.5 kg lost per week with no flying
• Critical at less than 6 kg of feed left (higher than in winter!)

The higher critical figure in spring takes account of the fact that consumption is now considerably faster and you need a larger buffer.

Checklist: spring (March to April)

Regular checking:

• Weight checks increased to twice a week
• In bad weather: check every 2-3 days
• Weather forecast checked regularly (7-day outlook)

Keeping emergency feed ready:

• 2-3 kg of feed candy per colony in reserve
• Feed candy stored within easy reach (not something to go hunting for)
• Optional: liquid feed for milder spells

Recognising the warning signs:

• Weight loss of >1.5 kg a week in bad weather = warning sign
• Less than 6 kg of feed left with bad weather forecast = feed immediately
• Less than 4 kg of feed left = act promptly

Watching the flying activity:

• Are the bees flying on mild days?
• Is pollen coming in?
• Does the weight rise on flying days (= nectar coming in)?

With a bad-weather spell of more than 5 days:

• Check the weight beforehand
• With less than 8 kg of feed left, feed preventively
• Check every 2-3 days during the spell

Conclusion: spring is not the all-clear

If your colonies have come through the winter, that is a reason to be glad - but not a reason to be careless. The weeks from mid-March to mid-April are a critical phase that deserves at least as much attention as the depth of winter.

The most important points:

1. Strong colonies are particularly affected - they have the highest feed consumption
2. Consumption in spring is 4 to 5 times higher than in winter (1.2-2 kg/week instead of 0.2-0.4 kg/week)
3. Two to three weeks of bad weather can be enough to bring a well-supplied colony into a critical situation
4. Check more often, not less often than in winter
5. Have emergency feed to hand - do not go and get it only when things are getting tight
6. Act sooner - in spring you have less time to react

With a digital hive scale you have a decisive advantage here: you see how things are developing in real time and can react before it becomes critical. But you can bring your colonies safely through this phase with manual checks too - as long as you know what to look out for.

The nectar flow is coming - and with the right preparation your colonies will be ready for it.

Have you had experience of feed shortages in spring? Share your story: info@honeylink.io

Further reading:

• Part 1: Winter feeding - the weight figures you should keep an eye on
• FAQs on hive scales

About the author: Dr.-Ing. Frank Steyer is managing director of Honeylink and a passionate beekeeper himself. His own experience at the apiary feeds directly into product development. Honeylink has been developing digital solutions for modern beekeeping for several years - by beekeepers, for beekeepers.