Methods for Collecting Propolis from Beehives

Propolis – often called “bee glue” – is a sticky, resinous substance that honeybees produce by collecting plant resins and mixing them with beeswax, saliva, and their own enzymes. It plays a critical role in hive maintenance, from sealing cracks to fighting off pathogens. For beekeepers, propolis is also a valuable hive product with growing commercial demand. But collecting it properly requires the right technique, timing, and tools. This post breaks down exactly how bees gather propolis, what they do with it inside the hive, and how beekeepers can harvest it efficiently without harming the colony.

What is propolis and what is it made of? 🔗

Propolis is a complex mixture primarily composed of resins (50-70%), waxes and fatty acids (25-35%), essential oils (about 10%), and pollen (roughly 5%). To date, researchers have identified over 500 bioactive compounds in propolis, including flavonoids like chrysin, galangin, pinocembrin, and quercetin, as well as phenolic acids such as caffeic acid, cinnamic acid, and p-coumaric acid. These compounds give propolis its well-documented antibacterial, antifungal, antiviral, and anti-inflammatory properties.

The exact chemical profile of propolis varies significantly based on the geographic location, the plant species available near the hive, and the season of collection. For instance, bees in temperate regions primarily collect resins from poplar, birch, pine, and other deciduous trees, while bees in tropical regions may source resins from entirely different plant families.

How bees collect propolis from plants 🔗

Bees don’t collect propolis in its finished form. What they actually gather are raw plant resins – sticky substances exuded by tree buds, bark wounds, sap flows, and leaf surfaces. These resins serve as the plant’s own defense mechanism against bacteria, fungi, and insects. Bees tap into that protective chemistry for their own purposes.

The foraging process 🔗

Only a small percentage of worker bees in a colony are dedicated to resin collection. The process works like this: a forager bee bites off a chunk of resin using her mandibles, works it with saliva to soften it, then transfers it from her forelegs to her mid legs, and finally packs it into the corbiculae (pollen baskets) on her hind legs. Each pollen basket can hold approximately 10 mg of resin.

This collection can only happen on warm days when the resin is soft and pliable. On cold days, resin hardens and becomes impossible to work with. Bees even use dance language to communicate the location of rich resin sources to other foragers, similar to how they share information about nectar.

Unloading at the hive 🔗

Here’s an interesting detail that sets propolis collection apart from pollen gathering: resin foragers cannot unload themselves. The material is so sticky that once a forager returns to the hive, other middle-aged worker bees must scrape the resin off her hind legs. These hive bees then mix the raw resin with beeswax and salivary enzymes to create the final product – propolis – which is now softer, more workable, and ready for use throughout the hive.

How bees use propolis inside the hive 🔗

Propolis is not just construction glue. It is a multifunctional material that contributes directly to colony health and survival.

Sealing gaps and cracks 🔗

Bees use propolis to seal gaps smaller than about 6 mm in the hive structure. Larger gaps (above roughly 9 mm) are typically filled with beeswax comb instead. This sealing behaviour helps the colony control airflow, maintain stable internal temperatures, and block entry points for pests and predators.

Sterilizing the hive environment 🔗

Propolis functions as the colony’s built-in disinfectant. Bees coat the interior walls, particularly the brood cells where the queen lays eggs, with a thin layer of propolis. This creates a hygienic surface that inhibits bacteria, fungi, and viruses. Research published in the Journal of Insect Science has shown that colonies with higher propolis deposits have lower pathogen loads, reduced immune stress, and better overall health.

Mummifying intruders 🔗

When a large intruder – such as a mouse or beetle – dies inside the hive and is too heavy for bees to remove, the colony encases it entirely in propolis. This mummification process neutralises the decomposing carcass, preventing it from releasing harmful bacteria into the enclosed hive environment.

Narrowing the hive entrance 🔗

Bees often apply propolis at the hive entrance to reduce its size. A smaller opening is easier to defend against robber bees, wasps, and other threats. The word “propolis” itself comes from the Greek words pro (before) and polis (city) – meaning “defence of the city.”

Methods beekeepers use to collect propolis 🔗

Beekeepers have two main approaches to collecting propolis: scraping and trapping. Each has advantages and trade-offs in terms of yield and quality.

Method 1: Scraping with a hive tool or knife 🔗

The simplest method is to scrape propolis off frames, box edges, and other hive components during routine inspections using a standard hive tool or stainless steel (inox) knife. Beekeepers often accumulate scrapings over several inspections throughout the season.

The downside of this method is that scraped propolis tends to contain contaminants – bits of wax, wood splinters, dead bees, and other debris. According to Utah State University’s beekeeping extension, this approach typically yields only small quantities of propolis per session. However, it’s a practical option for beekeepers who are already performing inspections and want to collect propolis as a secondary activity.

Method 2: Using propolis traps 🔗

Propolis traps are the preferred method for beekeepers who want cleaner, higher-quality propolis in larger quantities. A propolis trap is essentially a thin, flexible plastic sheet with narrow slits or small holes – similar in concept to a queen excluder but with openings too small for bees to pass through.

Here’s how it works:

Step 1 – Placement: The trap replaces the inner cover at the top of the hive. The beekeeper props the outer cover slightly open to allow some light and air into the hive. This stimulates the bees’ natural instinct to seal those gaps, and they begin filling the slits in the trap with propolis.

Step 2 – Wait: Over days to weeks, the bees progressively fill the trap. The speed depends on the colony’s propolising tendency, the season, and available resin sources.

Step 3 – Removal: Once the trap is sufficiently filled, the beekeeper removes it from the hive and places it in a plastic bag.

Propolis traps are inexpensive (typically under $10) and commercially available from most beekeeping supply companies. Some beekeepers also make DIY traps from corrugated plastic sheets with drilled holes smaller than 3/8 inch.

Best timing for propolis collection 🔗

Timing matters significantly for propolis yield. Late summer and early fall are generally the most productive periods for propolis collection. During this time, days are still warm enough for resins to be pliable, but cooling night temperatures trigger the colony’s instinct to winterize the hive. This leads to a spike in propolising activity.

Spring can also be productive as bees repair winter damage and prepare the hive for the active season. However, extremely hot days should be avoided for actual harvesting, because propolis becomes very sticky and difficult to handle in high temperatures. Conversely, very cold conditions make it too brittle and prone to fragmenting into tiny unusable pieces during scraping.

On average, a single hive can produce about 50-100 grams of propolis per season, though this varies considerably depending on the bee genetics, local flora, and collection method used. Some bee races, such as Caucasian bees, are known to be especially heavy propolis producers.

Encouraging bees to produce more propolis 🔗

Beekeepers can take a few simple steps to stimulate higher propolis production:

Roughen interior surfaces: Research from the University of Georgia found that textured hive interiors encourage bees to deposit more propolis compared to smooth-walled boxes. Lightly sanding the inside of hive bodies creates surfaces that trigger the bees’ propolising response.

Create small gaps and crevices: Cracks and openings smaller than the standard bee space (about 8 mm) prompt bees to seal them with propolis rather than build comb. Slightly increasing ventilation or introducing controlled drafts can also boost propolising behaviour.

Use multiple collection points: Rather than relying on a single trap, placing traps or rough surfaces at multiple locations within the hive distributes the collection activity and can increase overall yield.

Storing and processing collected propolis 🔗

Proper post-harvest handling is essential to maintain propolis quality. The key steps involve freezing, cleaning, and fragmentation.

Freezing 🔗

Immediately after removal from the hive, propolis (whether in a trap or as scrapings) should be sealed in a plastic bag and placed in a standard freezer for at least a few hours – though many beekeepers prefer 24 hours or longer. Propolis is soft and sticky at hive temperatures (above 19°C), but it becomes hard and brittle when cold. This brittleness is what makes the next step – fragmentation – much easier.

Cleaning 🔗

If using a trap, cleaning is straightforward: simply flex the frozen plastic sheet and the brittle propolis cracks off cleanly in small sticks or pieces. Trap-collected propolis is relatively pure and requires minimal further cleaning.

Hive scrapings, on the other hand, need more processing. One common technique involves soaking the scrapings in a pail of water. Contaminants like dead bees, wood chips, and beeswax tend to float, while propolis sinks to the bottom. This simple gravity separation removes most debris. Another method is to bake the scrapings in an oven-proof container with water at about 93°C (200°F) for at least two hours, stirring regularly to release trapped wax.

Fragmentation 🔗

Frozen propolis can be broken down into smaller pieces using several approaches: placing it in a heavy-duty bag and crushing with a rolling pin, using a dedicated mortar and pestle, or a coffee grinder reserved exclusively for propolis. The finer the fragmentation, the better the propolis can be dissolved in solvents like ethanol for tincture production. However, grinding for too long can generate heat that re-softens the propolis and makes it sticky again, so work in short bursts and return material to the freezer as needed.

Important considerations for quality propolis 🔗

Not all propolis is equal. Several factors influence the quality of what beekeepers collect:

Chemical contamination: If the hive has been treated with synthetic miticides or other chemicals for varroa mite control, those substances may be present in the propolis. Beekeepers intending to sell propolis for human use should be mindful of their treatment history.

Labelling and traceability: It’s good practice to label all collected propolis with the hive source and collection date. This helps with quality control and traceability, especially if propolis from different hives or seasons has different properties.

Avoid rolling into balls: As noted by Bees for Development, harvested propolis should never be rolled into a ball. Doing so traps debris, dust, and wax inside, reducing the overall purity and making later cleaning more difficult. Instead, store propolis as flat pieces or loose fragments.

Why propolis collection matters for beekeepers 🔗

Propolis represents an additional income stream beyond honey, beeswax, and pollen. Raw propolis can be sold directly to supply companies, processed into tinctures using ethanol, or incorporated into salves, creams, and other health products. The growing interest in natural antimicrobial and antioxidant products continues to drive demand.

At the same time, beekeepers should remember that propolis is essential to colony health. Studies have shown that propolis helps colonies maintain lower pathogen loads and reduces the energy bees spend on immune responses. Removing too much propolis can compromise hive hygiene, so a balanced approach – harvesting from honey supers or dedicated traps rather than stripping the brood nest – is the wisest strategy.

What do you think? Have you noticed differences in propolis production between bee colonies or across different seasons? And if you’re collecting propolis, what method – scraping or trapping – has worked best for you in terms of yield and quality?

References

1. https://beeculture.com/propolis/
2. https://pmc.ncbi.nlm.nih.gov/articles/PMC9504311/
3. https://beeculture.com/processing-propolis-part-1/
4. https://americanbeejournal.com/propolis-and-the-resin-connection/
5. https://beelab.umn.edu/propolis
6. https://en.wikipedia.org/wiki/Propolis
7. https://entomologytoday.org/2018/11/28/propolis-how-beekeepers-encourage-better-hive-health/
8. https://extension.usu.edu/beekeeping/research/propolis-harvest-and-use
9. https://horizontalhive.com/faq-knowledge-base/collect-harvest-propolis.shtml
10. https://coloradobeekeepers.org/what-to-do-with-all-that-propolis/
11. https://resources.beesfordevelopment.org/rc/propolis-3/
12. https://pmc.ncbi.nlm.nih.gov/articles/PMC8156449/