Tropilaelaps are brood parasites native to the wild honey bee species Apis dorsata, A. laboriosa and A. breviligula in south-east Asia. However, they have been found infesting managed colonies of the European honey bee, Apis mellifera, in many parts of Asia. Tropilaelaps have had a devastating impact on European honey bee colonies where they are present.
There are four recognised species of Tropilaelaps: Tropilaelaps clareae, T. mercedesae,T. koenigerum and T. thaii. Of these, only two are adapted to parasitise European honey bees: T. clareae and T. mercedesae. European honey bee populations infested with T. clareae are currently restricted to the Philippines, but populations infested with T. mercedesae are widespread throughout Asia, so this species presents the highest risk of being introduced into Europe and the UK.
Description
Tropilaelaps mites have elongated bodies about 1 mm long and 0.5 mm wide and are light orangey brown in colour. Males are slightly smaller than females. Tropilaelaps are about one-third the size of Varroa mites and move much more quickly. As Tropilaelaps are brood parasites, they have a similar lifestyle to Varroa mites in some respects. One or multiple females can invade a honey bee brood cell just before it is capped in order to reproduce and will feed from the developing larva or pupa as it develops. A female Tropilaelaps mite will lay its first egg 10 hours after the cell is capped and will continue to lay eggs at 24 hour intervals. Timings may vary in different climates and the development process can take between six and nine days.
Dorsal view of a Tropilaelaps mite.Distribution
The Tropilaelaps group of mites is native to south-east Asia, but Tropilaelaps mercedesae only began infesting colonies of European honey bee around 50 years ago and have expanded beyond their native range in Asia to China, Pakistan, Afghanistan, Papua New Guinea and possibly Iran. They infest honey bees in tropical and temperate climates.
In 2024, European honey bee colonies infested with T. mercedesae were reported in regions of Russia that are within Europe and its presence has been confirmed in Georgia. Its presence is also suspected in Uzbekistan, Tajikistan, Crimea, Belarus and Azerbaijan. As the mites are confirmed to be present at the eastern edges of Europe, this has heightened concerns that Tropilaelaps will spread westwards across Europe, in a similar way to Varroa decades earlier.
Although the Tropilaelaps mite is currently at the eastern edges of Europe, there is a significant risk that it will spread further into Europe, eventually reaching the UK. Tropilaelaps can thrive in both tropical and temperate climates and broodless conditions do not seem to limit its spread, even into regions where other host honey bee species are not present.
Countries and regions where T. mercedesae infestations are reported (red) or suspected (orange) in A. mellifera colonies. Inset: close up of eastern Europe and the Caucasas. Current as of December 2025. Map created using mapchart.net
Monitoring and reporting
In the UK, Tropilaelaps is a statutory notifiable pest and there is legislation in place to prevent its introduction and spread. Tropilaelaps mites are smaller, spend less time on adult bees, and move much faster than Varroa mites, making them more difficult to spot in a busy honey bee colony. Methods typically used for Varroa monitoring can be less sensitive for monitoring for Tropilaelaps. The methods described in our advisory leaflet on Tropilaelaps can be used for routine monitoring in colonies. If you photograph or capture any suspicious looking mites, please contact the NBU or SASA (for beekeepers in Scotland) immediately. If possible, collect a sample and freeze it.
Contingency Plans
Please follow the links below to download our Contingency Plans which outline proposed action in the event of an introduction of Tropilaelaps into England or Wales: Pest Specific Contingency Plan Small Hive Beetle and Tropilaelaps mite
Further information is available on our Contingency Planning BeeBase page.
New Tropilaelaps Rapid Pest Risk Analysis
Following the confirmed findings of Tropilaelaps mites in Russia and Georgia in 2025, concerns have been raised that these ectoparasites of honey bee brood are spreading. Therefore, Defra have produced a Rapid Pest Risk Analysis (PRA) to re-assess the risk posed to UK apiculture by Tropilaelaps mites.
Further reading
To learn more about Tropilaelaps mites and their impact on honey bees, please read our advisory leaflet on Tropilaelaps.
For more information on this pest please read the OIE Chapter on Tropilaelaps mites