What Is Braula Fly? A Beekeeper’s Guide

A beekeeper checking for braula fly

The braula fly is a tiny wingless fly with a flat, reddish body that beekeepers sometimes mistake for varroa mites. Found on every continent with bees, this insect is a minor pest for honey bees.

This guide closely examines the braula fly’s appearance, lifecycle, detection, and control.

NameBraula fly
Scientific NameBraula coeca
Alternative nameBee louse


The braula fly is a hairy reddish-brown fly with six legs and no wings. Measuring 1.5mm long, it resembles the varroa mite, tropilaelaps mite, and pollen mite.

Braula flies lay small white eggs throughout the hive, but the ones laid on capped honeycomb are the only ones that hatch.

Macro image of a braula fly
The Braula coeca looks similar to a varroa mite.

Symptoms and detection

If left untreated, the braula fly can negatively impact the colony. Their larvae make narrow 1mm tunnels under the wax cappings, which result in the comb appearing cracked. Beekeepers should look for uneven burrowing paths commonly made by this pest.

The braula fly is bigger than similar mites, making visual identification effective. Look at the top and sides of the adult bees for their presence.

Check the queen for signs of the fly on her abdomen or thorax, as she is a popular target.

Another detection method is placing a sticky mat on the hive’s bottom board. A few puffs of a smoker containing a small amount of tobacco will cause some mites to fall onto the mat.

Other symptoms associated with braula fly include:

  • Malnourished queen: Once a queen becomes infested with braula flies, she will have difficulty eating. This may lead to reduced egg laying and, in time, a reduced hive population.
  • Reduced honey production: Excessive honeycomb damage from tunneling may result in less honey output. 
Photograph of a cluster of honey bees and an arrow pointing at a bee with a braula fly on its thorax.
Spot the wingless braula fly.

Braula fly vs. varroa mite

While both insects are flat, red insects found on honey bee bodies, the varroa mite has eight legs and measures 1.1mm in length. Braula flies are half the width, have six legs, and are a little longer at 1.5mm long.

Both pests can harm the colony, but only the varroa mite develops in the hive’s bee brood as a parasite. This distinction makes the varroa mite a much bigger threat to beekeeping.


  • Braula coeca Nitzsch
  • Braula orientalis Òròsi Pál
  • Braula schmitzi Òròsi Pál
  • Braula pretoriensis Òròsi Pál
  • Braula kohli Schmitz


Braula flies develop from egg to adult in 10-21 days. The stages in their lifecycle include the following:

  1. Depending on the temperature, eggs are laid on capped honey and hatch within 2-7 days.
  2. Larvae tunnel into the wax cappings feeding on pollen and honey, and go through three larval stages.
  3. Pupation occurs after 7-11 days. This stage lasts 1-3 days before the adult emerges.
  4. After mating, the adult braula fly finds a host honey bee and attaches itself using claws that clasp the bee’s hair. As the bee feeds, the fly will move to the host’s head and steal food.
  5. The adult fly overwinters on an adult bee, then lays eggs next spring.
Zoomed in shot of a braula fly on a beekeeper's gloved thumb
The braula fly has six legs and is tiny.


Treating hives for braula fly is only required in extreme cases. These pests don’t usually impact honey bee health or yield.

If beekeepers choose to control these mites, they can use tobacco-infused smoke. Only use this approach with heavily infested hives, as it can affect bees if used excessively.

Treating varroa mites with chemicals will also kill Braula coeca; however, the use of miticides only to control these flies is overkill.

Freezing honeycomb for 48 hours will kill braula fly in egg, larvae, and adult stages.

During the honey extraction process, eradicate the larvae by uncapping the comb.

Related reading:

Commonly asked questions

Is the braula fly a threat to honey bees?

Braula flies steal small amounts of food from the hive, while the larvae cause damage to honeycomb wax cappings. In high numbers, these insects may cause the queen to lay fewer eggs resulting in supersedure. From a beekeeper’s perspective, the larvae can impact comb sales as burrowed honeycomb is less appealing.

Recent research has found the braula fly carries viruses . Skip down the page to read our summary of the research.

How does braula fly spread?

Braula flies attach themselves to adult bees and transfer to new hives during swarming, robbing, drifting, and absconding. They can also get transported on honeycomb and in bee packages and nucs. 

Where is the braula fly found?

The braula fly lives on all continents except Antarctica. In 2022, it was spotted for the first time on Australia’s mainland.

The braula fly often sits on flowers waiting to attach themselves to honey bees.

Did you know? Varroa mite miticide treatments have also been found to work on braula fly.

Image of a braula fly parasite on a bee's back
A bee colony can usually withstand the braula fly.

New research about the braula fly

We read the latest scientific research relating to the braula fly. Here’s our quick summary of the work:

The exceptional attachment ability of the ectoparasitic bee louse Braula coeca (Diptera, Braulidae) on the honeybee.

Our summary: Bee lice are tiny parasites that live on common honey bees. Falling off the bee means certain death for the louse. To stay attached, they have feet with claws with gaps to securely grip the bee’s hair.

Researchers studied braula fly feet to understand how they attach to the bee. Advanced microscopy and high-speed videos were used to observe the louse.

The researchers discovered that when the bee’s hairs slide into the narrow spaces between the claws, the louse gets a firm grip. It is so strong that it can hold onto 1130 times its body weight.

The louse’s feet also have features that prevent them from bending too much, which helps with staying attached. If necessary, they can also detach quickly.

Read the research>

Detection of Honey Bee (Apis mellifera L.) Viruses in the Inquiline Braula coeca and Comparison with Viruses in the Ectoparasite Varroa destructor.

Our summary: Honey bee colonies are home to bees and other small creatures that benefit from the hive. Among these are harmful parasites like the Varroa destructor mites and others like the Braula coeca flies, which live harmlessly inside.

While we know the Varroa mite spreads bee viruses, we haven’t looked much into whether the Braula coeca fly does the same.

This study aimed to find out if these flies carry common bee viruses. After testing, researchers found that the Varroa mite and the fly had three types of viruses.

Interestingly, the most dangerous virus was more common in the Varroa mite than in the fly.

This is the first time bee viruses have been found in Braula coeca flies, so more research is needed to understand how they get these viruses and if they can spread to bees.

Read the research>


  1. University of Florida Entomology and Nematology
  2. Morse RA, Flottum K. (eds.) 1998. Honey Bee Pests, Predators, and Diseases. 3rd edition. A.I. Root Company, Medina, Ohio. 718 pp.
  3. Smith Jr. IB, Caron DM. 1985. Distribution of the beelouse, Braula coeca, in Maryland and worldwide. American Bee Journal 125: 294-96.

Image credit:

Images are Courtesy The Animal and Plant Health Agency (APHA), Crown Copyright

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