Braula fly fact sheet

The Braula fly (Braula coeca) is a small species of wingless fly that lives in honey bee colonies.

The Braula fly is not considered to be a serious threat to commercial beekeeping as it does not damage or parasitise any stage of the honey bee life cycle however it can affect the appearance of honeycomb.

Braula fly larvae damages the appearance of the wax cappings on honeycomb and adult Braula flies steal small amounts of food from adult honey bees.

It was detected in Victoria in 2022, but has not yet been reported in other mainland areas of Australia. You must report Braula fly to the Exotic Plant Pest Hotline 1800 084 881 if detected.

What is Braula fly?

The Braula fly lives in honey bee colonies and attaches itself to honey bees where it feeds on nectar and pollen at the honey bee’s mouth and on material secreted by the host. Its presence may reduce the egg-laying capacity of queen bees resulting in queen supersedure and could make the detection of other exotic external parasitic mites difficult.

What does it look like?

Braula fly is small and wingless

The Braula fly is a small (0.9 mm wide by 1.5 mm long) wingless fly, it is red-brown, covered in hairs, and has six legs. The Braula fly lay small eggs (0.84 mm by 0.42 mm) throughout the hive, however, only the eggs deposited on capped honeycomb will hatch.

The hatched larvae tunnel under the cappings leaving narrow tracks about 1 mm wide across the surface of the comb. This tunnelling gives the comb a fractured appearance, a key characteristic of Braula fly presence.

Fractured appearance of honey comb from burrowing Braula

What can it be confused with?

Braula fly can be confused with the exotic parasitic Varroa mites (Varroa destructor and V. jacobsoni) and tropilaelaps mites (Tropilaelaps clareae and T. mercedesae).

Braula fly (top), varroa mite (right), tropilaelaps mite (bottom) and pollen mite (left)

Adult female varroa mites are oval, flat, red-brown, and 1 mm long and 1.5 mm wide. Tropilaelaps mites are active, red-brown mites which are around 1 mm long and 0.5-1 mm wide. Braula fly could also be confused with pollen mites (Mellitiphis alvearius) which are light brown and around 0.75 mm long and 0.75 mm wide. Pollen mites are naturally found in Australian hives and are not harmful to honey bees but are sometimes found in hives.

How is it spread?

Braula fly can spread through swarming or absconding honey bee colonies and drifting honey bees. Braula fly can also spread through the interchange of hive components from apiary to apiary, as well as the movement of hives. The larvae can also be spread by the removal and transport of infected honeycomb.

What should beekeepers look out for?

Braula flies have a preference to attach to queen bees but are regularly observed on drones and worker bees.

Hives should be thoroughly and regularly checked paying close attention to the queen bee. Beekeepers should also inspect capped honeycomb for tunnelling damage as this might be an indication of the presence of Braula fly.

Braula fly on the thorax of a bee

How can beekeepers protect their hives from Braula fly?

Beekeepers are advised to visually inspect and monitor their hives regularly and consider the following control measures:

  • Test for exotic pests – look for varroa mite, tropilaelaps, and Braula fly using visual inspection, sugar shake test, alcohol wash test, and brood uncapping methods.
  • Freezing (-15°C) comb honey for at least 24 hours will kill all life stages of the Braula fly.
  • The normal practice of extracting honey is another effective means to control the larval stage of the Braula fly as the eggs and larvae are removed with the wax cappings and can be processed (frozen or melted).

Reporting an unusual pest or disease of plants or honey bees

Report any unusual plant pest or disease immediately using our online reporting system. Early reporting increases the chance of effective control and eradication. Please take good quality photos of the pests or damage to include in your report where possible.

Alternatively, you can call the Exotic plant pest hotline on 1800 084 881.

Report online

Sources

Plant Health Australia

Images

Fig 1. Simon Hinkley and Ken Walker Museum Victoria, PADIL

Fig 2. NSW DPI

Fig 3. The Food and Environment Research Agency (Fera), Crown Copyright

Fig 4. The Food and Environment Research Agency (Fera), Crown Copyright

Page last updated: 20 Jan 2023