Bee Science: Spring Colony Growth - Managing Expansion, Nutrition, and Swarming

Managing Spring Colony Growth

Dr. Dewey Caron: Hi, I'm Dr. Dewey Caron. I come to you from Portland, Oregon.

I present another audio postcard in this once-monthly Beekeeping Today miniseries podcast, Bee Science with Dr. Dewey Caron. This is the fifth installment in this series. Each episode seeks to blend research, field experience, and seasonal context, focusing on the why behind honey bee biology and behavior.

I welcome your suggestions for timely topics you'd like to have covered.

The mini-series this month is spring. Spring is continuing. For some of us, we're well into the spring and beyond. Others are kind of beginning for our listeners, so there is variation.

For the previous two episodes, I discussed mites and how we should have a plan — how to flatten the mite growth curve in the spring. My overall message was fairly simple: have a plan.

With new tools and better information about the varroa mite's early spring reproduction, especially in drone brood, your plan may now be evolving. You may have modified your plan to include use of OAV, for example Varroxan, or the homemade sponges soaked in oxalic acid.

Some additionally have added a spring chemical treatment, and hopefully most are including some drone brood removal in their plan. Others are seeking to integrate NOROA, the double-stranded RNA treatment regime that causes a halt in varroa mite reproduction.

So, on to our topic this month: spring.

Spring is a period of population increase. Availability of pollen and weather appropriate for foraging flight are major drivers of spring colony expansion. For southern sites, this period of spring expansion is drawn out and occurs gradually, while for more northern locations this period can be short and the population increase very rapid.

There are many good resources about management of spring colonies: bee club websites, bee club newsletters, articles in our sponsored Bee Culture magazine — for example the regular column in March 2026 by Jim Tew entitled “Giving It Your Best Guess” — YouTube, and many more. Pick and use one or more appropriate for your area.

Many sources on spring management recommend feeding dilute sugar syrup and/or protein patties to improve spring colony development. Feeding extends the resources for days when environmental conditions may limit flight, but only works provided the bees can break cluster to access those resources. In-hive feeding improves such access.

So what about protein?

A study demonstrating that protein influences spring colony development extends back to a 2006 article by Heather Mattila. Heather, in her PhD study with advisor Gard Otis at the University of Guelph, established pollen-supplemented and pollen-limited colonies for three springs. Colony brood rearing and honey yields were subsequently monitored throughout the summer.

In all three years, the colonies that were supplemented with pollen or a protein substitute in the spring started rearing brood earlier than colonies in other treatment groups and produced the most workers by late April or early May.

A 2018 publication by USDA researchers in Tucson demonstrated that there is a difference in colony response to fall and spring pollen, indicating supplements may be most beneficial with addition of pollen collected locally in the proper season for maximum effectiveness.

A recently published 2026 research paper by Kelly Kuehn and the folks at Washington State University examined a nutritionally complete feed resembling an oversized thin granola bar. It was developed by Apex Biosciences, a biotech company based in Belgium and Fayetteville, Arkansas. It is a new entry into a crowded and complicated supplemental bee feed market and has been nicknamed “Canadian Rocket Fuel.”

The study involved beekeeping operations each managing more than 2,000 colonies. Colonies of equally sized groups received either the new diet or the normal fall-winter feeding preference of each beekeeper.

Every participant continued the feeding cycle from the end of pollination season, when supplemental feeding normally starts, through the end of the California almond pollination season.

Colonies fed the new feed stayed healthier and performed better through winter and the almond pollination season. By January, during almond pollination, those colonies had more adult bees and more colonies met the requirements for premium pollination contracts.

After almond pollination, those colonies survived at higher rates. Winter mortality dropped from 28.8% with the commercial standard diets to 15% with the new feed — nearly a 50% mortality reduction.

Mann Lake is now selling this as Apis BioControl, also known as Rocket Fuel.

These studies are referenced at the end notes, along with the Honey Bee Health Coalition leaflet written by Pia Brossaud of Washington State University detailing bee nutritional products.

During the spring period of rapid growth, colonies may prepare to swarm. Swarming is the bees’ method of reproducing the colony.

Swarming starts by the bees raising new queens. As bee colonies expand in spring, regular inspections to keep ahead of growth and additional boxes for expansion of the brood and/or supers for nectar storage will reduce the chances that bees will start to raise queens. Good ventilation within the hive and plenty of comb space for queen egg laying helps too.

Threats to bee health are both external and internal to the beehive during this spring population increase period. A specific disease inspection should be conducted of spring colonies.

Diseases such as European foulbrood, chalkbrood, and sacbrood seldom kill colonies but may weaken colonies during the critical spring buildup period, depending upon severity.

Spring also brings potential exposure to pesticides and poisonous plants, and foragers outside the hive face numerous predaceous insects, spiders, and other occasional bee predators. Health issues may persist in weaker colonies or show up in colonies started as splits, nucs, or packages. The spring diseases and the adult fungal disease Nosema often disappear as colonies bring in abundant resources and foraging weather improves.

Colonies around crops and agricultural areas are in greater danger of pesticide loss. With peak population, the loss of foragers is less of an issue. Toward the end of this period, robbing of a weaker colony by stronger ones is a possibility.

Queen issues occur as bees seek to replace their single queen. Replacement may not be successful, and queenless colonies become susceptible to health issues. If not supered in a timely fashion, bees backfilling the brood area with incoming nectar can slow development and increase the probability of swarming.

Bee populations that are slow to develop or colonies preparing to swarm are colonies under stress. It is important to diagnose reasons for poor or less-than-expected colony development. In some instances it is possible to take remedial action.

Large spring colonies become very populous and make it difficult to detect developing health issues. Large amounts of brood also mean more opportunity for varroa mites to increase their population.

Drone brood removal initially can be used to assess reproduction as well as reduce varroa reproduction. Weaker colonies and new colony starts need continual vigilance.

So what is normal? What is normal for spring colony development?

Assessing whether overwintered colonies are strong, weak, or just right in adult numbers or brood populations — the Goldilocks effect — is one of the toughest determinations for new and especially inexperienced beekeepers.

Maintaining more than one colony, plus experience with different seasons, helps with determining weak versus strong.

So what is this Goldilocks evaluation?

Remembering the story of Goldilocks and the Three Bears, Goldilocks found one bowl too hot, one too cold, but one just right. Our spring colonies might be too strong or too weak, but hopefully most will be just right. I wrote about the Goldilocks effect in the BMD app that you can access on the entry covering seasonal colony management.

A common method to determine if a colony is weak or strong is to split the two boxes — assuming the colony was overwintered in two boxes — what we call clamshelling, and look both below and from above into the top box.

If in doubt, remove frames and actually count frames with active brood rearing.

If brood occurs on more than half of the frames, consider it a strong colony. A weak colony may have brood with barely enough bees to cover a quarter of the frames in one box, sometimes only one or two frames.

Colonies that are just right will have brood in both boxes, likely more in the top box, and roughly half the frames will have brood with bees to cover. This assessment of size will vary with season, of course.

Colonies that are strong need to be reduced in both frames of brood and adult bees. Frames can be moved from strong colonies to weaker colonies to strengthen them, provided there are no disease issues in the apiary.

Weak colonies can be stimulated with sugar syrup.

As spring nectar availability increases, supers need to be added to stronger colonies to avoid bees using cells the queen might use for egg laying as storage and ripening space for nectar.

I’ll cover additional supering management in Bee Science next month.

Media posts from local bee clubs can alert individuals to seasons when bees are developing more rapidly or are delayed. With bees, timing is everything. Strong or weak refers not only to adults but also to developing brood populations.

Initially, the adult population is balanced with overwintered older-age bees. Rearing replacement bees by colonies with aged adult populations is slower.

There is variation in queen egg laying, with younger queens more likely to be better egg layers.

Locations where early pollen sources are reliable favor faster expansion. City and suburban sites often have many pollen sources available and are good sites for spring expansion.

Early spring weather followed by a cooler, wetter spring may dampen spring colony expansion. Colonies, especially stronger ones, may starve if they expand too rapidly and weather limits continued foraging for several consecutive days.

On the other hand, overstimulation by early feeding of sugar syrup and/or protein supplementation may help mitigate poor spring weather, but it can also lead colonies to grow rapidly and prepare to swarm.

Frame manipulations may help both weak and strong colonies. Transferring frames from stronger to weaker colonies is one option. Reducing the space in hive boxes may help weak colonies. Use a solid divider board to bring outside walls closer together to better confine weaker hives in large boxes.

Divider and follower boards are essential if you manage long hives or top bar colonies.

Reversing hive bodies by moving the top box down to the bottom board and placing the mostly empty bottom box on top helps stronger colonies continue their preferred upward expansion. However, reversing too early may negatively affect colonies if cluster location is between the boxes.

Adding frames of foundation to stronger colonies and moving drawn comb frames to weaker colonies is often beneficial. Later in spring expansion, assuming the colony is large enough, a second reversal will not put the colony at risk.

Moving frames in stronger colonies to spread out brood rearing can be useful, but be mindful of how bees organize their nest. You can do more harm than good by pushing expansion or doing reversals too early when resources are limited.

Dwindling or collapse is a catch-all term for the sudden disappearance of bees, slow development of overwintered colonies, or spring loss of colonies that initially survived winter. Other names include disappearing disease, May disease, or spring starvation. Spring dwindling is more common in colonies weakened during winter or colonies with older queens or queen replacement issues.

There may simply be too few bees to grow from the weakest winter survival point, and the bees cannot take advantage of spring flowering resources. Colonies may dwindle and develop slowly while neighboring colonies are storing harvestable surplus honey. A dearth of pollen may reduce brood rearing depending on the amount of stored bee bread.

Growing spring colonies may have a break in the brood cycle due to queen replacement, swarming, or external factors such as pesticide poisoning.

Management options such as making splits can also create a brood break. Treatment with formic acid may likewise create a brood break that reduces overall population size. A brood break may not reduce honey production potential if it occurs close to or during the nectar flow of peak population. In fact, it may free bees from nursing duties and increase foraging potential.

A brood break created for mite treatment enables effective use of oxalic acid treatment because mites are then confined to adult bees rather than protected inside capped brood. The queenless portion of a split colony can therefore be treated effectively for mites. Management timing is critical.

A brood break created intentionally by the beekeeper can be effective management, whereas a brood break created by swarming preparations may reduce harvestable honey surplus. Bluntly, to prevent swarming, keep young queens in your colonies and provide extra brood space before it is needed.

If you see swarm cells — and sooner or later you will — make splits and hope for the best. Splitting a swarm-inclined colony may still lead to swarms. Put swarm traps out. Old retired equipment works well for this. I don’t know if I’ve ever truly stopped a swarm by destroying swarm cells. It makes more sense to proactively manage colonies before swarming begins.

Space matters.

Beekeepers using horizontal hives or top bar hives should consider follower boards to limit colony space to a manageable area. Divider boards are used to separate two hives within the same box. A two-frame nuc or small swarm placed into a large empty ten-frame box often struggles initially in excessive space. Limit the space and move the follower board gradually as the colony grows.

Spring is our busiest season. It starts slowly but quickly gains momentum. We can overmanage bees with feeding, protein supplements, or hive space manipulation. We need to flatten the mite growth curve but not flatten bee expansion. Getting the balance right is delicate because no two springs are exactly alike environmentally.

Stimulate colonies, transfer frames, weaken colonies considered too strong so they don’t swarm, and stay ahead with supering. There is a lot on our spring plate.

The message with this Bee Science episode is simple: listen often to your bees and treat each colony accordingly.

Good luck. Until next time, be well.