Citizen Science Winter Capped Brood Monitoring Program

a composite image of collaborator logos (left) and a hands taking out a hive frame with brood.

The US Winter Capped Brood Monitoring Project is underway for its fourth season. Every two weeks from October to February, Auburn University, along with other universities and USDA labs from across the country, inspects colonies for capped brood. This effort helps us understand the best times for winter oxalic acid mite treatments and which areas will be most at risk for another parasitic mite, Tropilaelaps, if it is introduced to the US.

Beekeepers: we need your help tracking capped brood across the US. This involves inspecting three hives (or fewer if necessary) for capped brood. We welcome data from Canadian beekeepers also!

Inspections should happen during three windows in December and January, detailed below:

INSPECTION WINDOWS

  1. Friday, December 19, 2025 to Sunday, December 21, 2025
  2. Friday, January 2, 2026 to Sunday, Janurary 4, 2026
  3. Friday, January 16, 2026 to Sunday, January 18, 2026

We ask that you please inspect your colonies during as many of these 3 event windows as possible. If you can only inspect colonies within one or two of these windows, we still want your observations!

Participate and submit your observations
Access our live results map

HOW DO I INSPECT COLONIES FOR CAPPED BROOD IN THE WINTER?

Each colony inspection should take 2-3 minutes.

  1. Smoke the colony.
  2. Remove supers or hive bodies until you can locate the cluster. If it is very cold, you may cover bees in removed boxes with an extra inner or outer cover.
  3. Make note of colony strength. We consider clusters about the size of a basketball to be “normal” strength. Weak colonies have smaller clusters (softball-sized or smaller), while strong colonies are much larger than a basketball.
  4. Carefully remove 1-3 frames from the center of the cluster. If there is capped brood on any of the frames, report “Yes” on the survey. If you find uncapped brood (eggs or larvae without wax cappings) and no capped brood, report “No” on the survey. Fewer than a dozen total capped brood cells that are chilled, dead, or not guarded by the bee cluster count as no brood.

For more information, refer to our video below:

WHAT DOES CAPPED BROOD LOOK LIKE?

Cells containing capped brood, or brood in the pupal stage, will have a slightly domed or convex wax capping. They have a rough, porous texture. This picture shows several dozen capped brood cells. If the inspected frame(s) looked like this, we would say yes, this colony has capped brood.

A colony may have eggs or larvae without wax cappings, but no capped brood. This picture shows both younger and older larvae. If the brood on all inspected frames looked like this, we’d say no, this colony does not have capped brood.

Capped honey is sometimes mistaken for capped brood. Compared to brood, the wax cappings on honey cells are smoother. The comb surface may have a rippled texture. This photo does not show any brood.
Often, bees in winter will form a tight cluster as they consume stored honey. Small patches of brood may still be present beneath the bees. In this case, we may need to move some bees aside to view the brood.

COLLABORATORS

This work is being supported through funding from the Southern IPM Center 2022-70006-38002, the USDA ARS Cooperative Agreement 58-6066-3-029, the USDA National Institute of Food and Agriculture 2022-70006-38002, and the USDA National Food Institute of Food and Agriculture Hatch Multi-state Project NC1173.  

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Contact

Geoffrey Williams
Associate Professor
301 Funchess Hall
Auburn, AL 36849
334-844-5068

Ben DeMoras
Ph.D. Student
952 Bee Lab Road
Auburn, AL 36849
bxd0001@auburn.edu