Guest Blog Post by Dr. Jana Christophoryová
Imagine living in a world where your home can disappear overnight.
For many tiny arthropods, such as pseudoscorpions, this is a reality. They inhabit ephemeral and unpredictable habitats – decaying organic matter, animal nests, or tree hollows – that can quickly vanish or become unsuitable. Without wings, escaping these disappearing habitats poses a serious challenge.
So how do they cope?
The answer lies in a fascinating strategy known as phoresy: hitchhiking on other, more mobile organisms. In the case of pseudoscorpions, these carriers are often flies.
Flies (Diptera) are particularly suitable transport hosts. They are highly mobile, capable of long-distance flight, and frequently visit the same types of transient habitats that pseudoscorpions depend on. By attaching themselves to a fly, pseudoscorpions can effectively outsource dispersal – reaching new habitats they could never access on their own.
Despite its importance, the relationship between pseudoscorpions and flies has remained largely underexplored. Comprehensive syntheses are more than two decades old, and much of the available knowledge has been scattered across individual studies, often published in different languages and difficult to access.
What began as a marginal aspect of our research gradually turned into a much greater effort. As we followed scattered records across the literature, it became clear that no up-to-date overview existed. This led us to examine hundreds of publications from different countries and time periods, critically reassessing old records while adding new data from our own material.
Altogether, we compiled 172 records spanning more than 250 years, from 1761 to 2025 – providing the most comprehensive overview of pseudoscorpion – Diptera phoresy to date now published in the open-access journal ZooKeys.
Our results show that pseudoscorpions have been recorded hitchhiking on at least 74 species of flies across 30 families, while the number of known pseudoscorpion travellers reaches 39 species from seven families. Several new host associations were identified, including seven fly species and three fly families not previously known to serve as carriers. We also documented 11 new cases of phoresy from Europe, including first national records for some species.
Interestingly, most records are linked to a single, familiar species – the house fly (Musca domestica). However, this pattern is likely influenced by historical research bias, as earlier studies focused heavily on this easily observable association. This highlights an important challenge: understanding phoresy requires not only new data, but also careful re-evaluation of past identifications.
Beyond modern observations, fossil evidence preserved in amber reveals that these interactions are far from recent. Pseudoscorpions were already hitchhiking on flies tens of millions of years ago, indicating that this dispersal strategy has deep evolutionary roots.
Taken together, our findings show that phoresy is not just an occasional curiosity, but a widespread and long-standing ecological strategy. It allows these tiny, wingless predators to navigate a fragmented and ever-changing world – by quite literally catching a ride.
Original source:
Christophoryová J, Mathy V, Hörweg C, Vičanová L (2026) Hitchhiking across continents: phoresy of pseudoscorpions (Arachnida, Pseudoscorpiones) on Diptera, with new European records. ZooKeys 1276: 213-248. https://doi.org/10.3897/zookeys.1276.188186
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