Two bars from a top bar hive that the bees have glued together using propolis. Separating the bars will take some effort as the propolis has hardened.
Propolis on the upper bar

Propolis or bee glue is a resinous mixture that honey bees produce by mixing saliva and beeswax with exudate gathered from tree buds, sap flows, or other botanical sources. It is used as a sealant for unwanted open spaces in the beehive. Propolis is used for small gaps (around 6 mm (14 in) or less), while gaps larger than the bee space (around 9 mm (38 in)) are usually filled with burr comb. Its color varies depending on its botanical source, with dark brown as the most common. Propolis is sticky above 19 °C (66 °F), while at lower temperatures, it becomes hard and brittle.

When foraging, worker bees primarily harvest pollen and nectar, while also collecting water and plant resin necessary for the production of propolis.[1] The chemical composition and nature of propolis depend on environmental conditions and harvested resources.[2]


Mixed types of propolis found in European countries with a moderate climate include two or more sources of plant resins (plant species) identified by composition, such as aspen, Mediterranean, poplar, Pacific, Brazilian green, Brazilian red, and Mangifera types of propolis.[3][citation needed]


Propolis drops in red (units in micrometers)

Bees seal the beehive with propolis to protect the colony from the elements, such as rain and cold winter drafts.

Propolis functions may include:[1]

  1. Reinforcing the structural stability and reduce vibration
  2. Providing improved thermal insulation to the hive and reduce water loss
  3. Providing protection from pathogens, via antifungal and antibacterial properties[4][5]
  4. Make the hive more defensible against parasites and predators by narrowing the existing entrance (in wild colonies) to a single "choke point"
  5. Mitigate putrefaction within the hive - bees usually carry waste out of and away from the hive, but if a small lizard or mouse, for example, finds its way into the hive and dies there, bees may be unable to carry it out through the hive entrance. In that case, they would attempt instead to seal the carcass in propolis, essentially mummifying it and making it odorless and harmless.


Propolis in hive

The composition of propolis varies from hive to hive, from district to district, and from season to season.[6] Normally, it is dark brown in color, but it can be found in green, red, black, and white hues, depending on the sources of resin found in the particular hive area. Honey bees are opportunists, gathering what they need from available sources, and detailed analyses show that the chemical composition of propolis varies considerably from region to region, along with the vegetation. In northern temperate climates, for example, bees collect resins from trees, such as poplars and conifers (the biological role of resin in trees is to seal wounds and defend against bacteria, fungi, and insects). "Typical" northern temperate propolis has roughly 50 constituents, primarily resins and vegetable balsams (50%), waxes (30%), essential oils (10%), and pollen (5%).[7] [8]An analysis of propolis from Henan, China, found sinapinic acid, isoferulic acid, caffeic acid, and chrysin.[9]

In neotropical regions, in addition to a large variety of trees, bees may also gather resin from flowers in the genera Clusia and Dalechampia, which are the only known plant genera that produce floral resins to attract pollinators.[10] Clusia resin contains polyprenylated benzophenones.[11][12][13] In some areas of Chile and Argentina Andean valleys, propolis contains viscidone, a terpene from Baccharis shrubs,[14] and prenylated acids, such as 4-hydroxy-3,5-diprenyl cinnamic acid.[15]

Overall, flavonoids, phenolic acids, and phenolic aldehydes are common constituents, while coumarins, stilbenes, and lignans are less common.[16]


Traditional medicine

Propolis has been used in traditional medicine, with insufficient evidence to rate its effectiveness in the treatment of any illnesses.[17]

Musical instruments

Propolis is used by some string-instrument makers (violin, viola, cello, and bass) as a varnish ingredient.[18] A tincture of propolis may be used to seal the surface of newly made violin family bridges, and may be used in the maintenance of the bores of pan flute tubes.[citation needed] Claims that Antonio Stradivari used propolis in the varnish of his instruments were disproven in 2009.[19][20]


  1. ^ a b Simone-Finstrom M, Spivak M (May–June 2010). "Propolis and bee health: The natural history and significance of resin use by honey bees". Apidologie. 41 (3): 295–311. doi:10.1051/apido/2010016. hdl:11299/182451.
  2. ^ Ferreira JM, Fernandes-Silva CC, Salatino A, Negri G, Message D (August 2017). "New propolis type from north-east Brazil: chemical composition, antioxidant activity and botanical origin". Journal of the Science of Food and Agriculture. 97 (11): 3552–3558. Bibcode:2017JSFA...97.3552F. doi:10.1002/jsfa.8210. PMID 28078783.
  3. ^ Popova M, Trusheva B, Bankova V (2022). "Chemistry and Applications of Propolis". Reference Series in Phytochemistry. Springer International Publishing. pp. 657–688. doi:10.1007/978-3-030-91378-6_38. ISBN 978-3-030-91377-9. ISSN 2511-834X.
  4. ^ National Geographic p. 83 03/2020
  5. ^ Walker M (23 July 2009). "Honeybees sterilise their hives". BBC News. Retrieved 24 July 2009.
  6. ^ Toreti VC, Sato HH, Pastore GM, Park YK (2013). "Recent progress of propolis for its biological and chemical compositions and its botanical origin". Evidence-Based Complementary and Alternative Medicine. 2013: 697390. doi:10.1155/2013/697390. PMC 3657397. PMID 23737843.
  7. ^ Wagh, Vijay D. (2013). "Propolis: A Wonder Bees Product and Its Pharmacological Potentials". Advances in Pharmacological Sciences. 2013: 308249. doi:10.1155/2013/308249. ISSN 1687-6334. PMC 3872021. PMID 24382957.
  8. ^ Burdock, G. A. (6 April 1998). "Review of the biological properties and toxicity of bee propolis (propolis)". Food and Chemical Toxicology. 36 (4): 347–363. doi:10.1016/S0278-6915(97)00145-2. ISSN 0278-6915. PMID 9651052.
  9. ^ Qiao Z, Chen R (August 1991). "[Isolation and identification of antibiotic constituents of propolis from Henan]". Zhongguo Zhong Yao Za Zhi = Zhongguo Zhongyao Zazhi = China Journal of Chinese Materia Medica (in Chinese). 16 (8): 481–2, 512. PMID 1804186.
  10. ^ Mesquita RC, Franciscon CH (June 1995). "Flower visitors of Clusia nemorosa G. F. W. Meyer (Clusiaceae) in an Amazonian white-sand Campina". Biotropica. 27 (2): 254–8. Bibcode:1995Biotr..27..254D. doi:10.2307/2389002. JSTOR 2389002.
  11. ^ Tomás-Barberán FA, García-Viguera C, Vit-Oliviera P, Ferreres F, Tomás-Lorente F (3 August 1993). "Phytochemical evidence for the botanical origin of tropical propolis from Venezuela". Phytochemistry. 34 (1): 191–6. Bibcode:1993PChem..34..191T. doi:10.1016/S0031-9422(00)90804-5.
  12. ^ Armbruster WS (September 1984). "The Role of Resin in Angiosperm Pollination: Ecological and Chemical Considerations". American Journal of Botany. 71 (8): 1149–60. doi:10.2307/2443391. JSTOR 2443391.
  13. ^ Bankova V (March 2005). "Recent trends and important developments in propolis research". Evidence-Based Complementary and Alternative Medicine. 2 (1): 29–32. doi:10.1093/ecam/neh059. PMC 1062152. PMID 15841275.
  14. ^ Montenegro G, Mujica AM, Peña RC, Gómez M, Serey I, Timmermann BN (2004). "Similitude pattern and botanical origin of the Chilean propolis". Phyton. 73: 145–154. ISSN 1851-5657. Archived from the original on 17 December 2014. Retrieved 7 November 2008.
  15. ^ Park YK, Alencar SM, Aguiar CL (April 2002). "Botanical origin and chemical composition of Brazilian propolis". Journal of Agricultural and Food Chemistry. 50 (9): 2502–2506. doi:10.1021/jf011432b. PMID 11958612.
  16. ^ Berenbaum MR, Calla B (January 2021). "Honey as a Functional Food for Apis mellifera". Annual Review of Entomology. 66 (1). Annual Reviews: 185–208. doi:10.1146/annurev-ento-040320-074933. PMID 32806934. S2CID 221165130.
  17. ^ "Propolis". MedlinePlus, U.S. National Library of Medicine. 11 May 2020. Retrieved 5 December 2020.
  18. ^ Fulton W (July 1997). "PROPOLIS SOAP – Used as a Ground for Violin Varnish". Southern California Association of Violin Makers. Retrieved 6 December 2020.
  19. ^ "Stradivarius varnish myth debunked". BBC Music. 8 December 2009.
  20. ^ "Secret behind the composition of the varnish on Stradivari violins revealed". 4 December 2009.