The Hidden Danger in Your Hive: How Contaminated Beeswax Can Undermine Bee Health and Productivity

If you're a beekeeper who recycles or reuses combs and foundation wax, this study is a must-read. A 2025 research paper by Benito et al. investigated pesticide residues in beeswax across 25 apiaries in western Spain, and the findings are a wake-up call for beekeepers everywhere, including in New Zealand.

What Did the Study Find?

Researchers analyzed beeswax samples and found an alarming presence of pesticide residues in all samples. Most residues belonged to a class of insecticides previously used to control varroa mites, particularly coumaphos, tau-fluvalinate, and amitraz. While many of these are no longer used or are banned, their persistence in beeswax is significant.

Some samples contained pesticide concentrations so high that they could pose toxicological risks to the bees, especially to developing brood. The presence of these compounds can disrupt larval development, queen fertility, and even worker behavior, ultimately reducing hive performance and honey yield.

The old comb that is ready to be replaced

Why This Matters to You

Old comb is not just old—it's potentially toxic. Beeswax is lipophilic, meaning it absorbs and retains pesticides over time. If you regularly reuse foundation or recycle wax without testing, you might be creating an invisible threat inside your hives.

What Can You Do?

• Rotate Out Old Comb: Replace combs regularly to minimize residue build-up.

  
  

• Test Wax if Possible: Especially if you’re producing foundation for your own or others’ use.

  
  

• Use Certified Wax Sources: Buy wax from trusted, tested, or certified pesticide-free suppliers.

  
  

This study reminds us that what bees walk and grow on every day matters just as much as what they eat. Clean wax means healthier bees—and healthier bees mean better beekeeping.

Read the entire study here: https://doi.org/10.1016/j.etap.2025.104744