Does UV-Blue Really Make a Better Swarm Trap?

I was first introduced to Brian Fleishmann’s September 2022 Bee Culture article, “Impact of UV-Induced Blue Fluorescence Entrances in Bee Culture,” through the MABA swarm trap build group. I was quickly convinced to give it a try. In 2023, I purchased four UV-reactive blue swarm trap entrances from the ApiTekStore. Not everyone in the swarm trap-building community was convinced. Brian’s experiment points toward a positive result, but with only six observations, the evidence isn’t strong enough to call the results statistically conclusive.  Still, I keep coming back to Brian’s experiment because, regardless of the statistical limitations, I think the experimental design is beautiful.

Brian’s article came to two conclusions:

• UV-reactive blue swarm trap entrances nearly doubled the number of scout bees observed compared with the control entrances.
• Swarms selected the trap with the UV-blue entrance over the control 100% of the time.

Those are pretty compelling results for a beekeeper looking for an edge in swarm trapping. Before getting too excited, it’s worth looking at how the experiment was conducted.

	Scout Bee Activity Logged	Trap Selected
Year 1 - 2020
Location 1	Yes	UV-reactive blue
Location 2		UV-reactive blue
Location 3		UV-reactive blue
Year 2 - 2021 (trap entrance swapped)
Location 1	Yes	UV-reactive blue
Location 2		none
Location 3		UV-reactive blue

Brian conducted the experiment from May through August in 2020 and 2021 in western New York.
The basic setup:

• Traps were attached to trees 8–10 feet above the ground.
• Each trap had a 1.25-inch (3.2 cm) circular entrance hole.
• Trap cavity volume was 1.59 cubic feet (45 liters).
• Each trap contained four frames without comb and one frame with some comb.
• Three locations faced open fields with bee forage.
• Two traps were placed at each location, approximately 200 feet apart.
• One trap had a 3D-printed entrance made from UV-reactive blue filament.
• The other used white filament as the control.
• Swarm lure spray was applied weekly.
• Weather permitting, one location was monitored for scout bees between 11:30 a.m. and 4:00 p.m.

There was also a particularly clever element to the 2021 experiment: the UV-reactive and control entrances were swapped between traps.  Why? To control for the possibility that the bees simply preferred one particular tree. That detail is one of the reasons I like the experiment so much. Brian wasn't just asking, “Do bees like blue?” He was trying to eliminate other explanations for the bees' behavior. 

The biggest weakness is the sample size.
With only six observations, the results don't provide the kind of statistical confidence needed to make a definitive claim that UV-blue entrances attract more swarms. A larger experiment with more traps, locations, and swarm events would be much more convincing.  

To see whether Brian's findings had any support from other research, I asked Perplexity to look for academic, peer-reviewed citations of his article. Unfortunately, it couldn't find any. That isn't necessarily surprising. Brian's article appeared in Bee Culture, a trade publication, rather than an academic journal.
Perplexity did uncover a related 2018 study by Ostroverkhova et al., “Understanding innate preferences of wild bee species: responses to wavelength-dependent selective excitation of blue and green photoreceptor types.” Brian also references this study in his article.  Ostroverkhova found that significantly more bees were captured in their “attractive” traps equipped with blue fluorescent vanes than in the other traps they tested, with a statistically significant result of P < 0.05.  That doesn't prove Brian's swarm-trap experiment was correct. The experiments were not identical, and we shouldn't treat them as interchangeable.  It does provide an interesting piece of supporting evidence: bees can show a measurable attraction to particular blue wavelengths.  So while Brian's experiment has limited statistical power because of its small sample size, its findings don't exist in complete isolation. They point in a direction that is also supported by a separate experiment with stronger statistical evidence.
 

Fast-Forward to 2026
My original UV-reactive PLA swarm trap entrances from ApiTekStore have now been through several seasons, and they're showing their age. The plastic has become brittle and the blue color has faded.  Then, in April 2026, I met MABA speaker Ryun Forsman, better known as The3DBee, who gave a presentation on 3D printing.  Ryun makes swarm trap entrances using durable PETG filament, and his design has a much larger footprint along with a stronger UV-reactive response than my original entrances.  I bought six and I’m putting them to work.

Here's a short video of scout bees visiting one of my traps on March 10, 2026.

On April 13 2026, at 12:30 PM all the scouts vanished and shortly after the swarm started to move in.  Here’s a time lapse video of the swarm arrival. 

There Is No Perfect Swarm Trap Recipe
At this point, I'm comfortable saying that UV-blue entrances add value to my swarm trap management.  There are many best-practice swarm trap variables that may never have a settled answer.  For example, I'll share two things I do differently from Brian's experiment:

1. I use a slow-release Nasanov pheromone vial.
2. I don't put old comb in my swarm traps.

Despite those differences, neither practice appears to have hurt my year-over-year success.  Swarm trapping isn't about finding a single magic recipe. It's about stacking the odds in your favor.