This ancient ant and its parasitic oppressor were trapped together for eternity when they became engulfed in tree resin in the Baltic region, some time between 49 and 44 million years ago. Researchers say that this is only the second known example of a fossilized mite attached to its host.

The 0.7-millimetre-long mite and its victim are preserved in amber, which is fossilized tree resin. The mite appears to be firmly attached to the ant’s head — a behaviour also seen in modern parasitic mites of the Varroa genus, which are often mentioned as possible culprits in the sudden collapse of honeybee colonies.

In a paper published on 10 September in Biology Letters1, researchers write that the mite belongs to the genus Myrmozercon, which includes numerous species still alive today. An air bubble trapped between the two invertebrates hides some anatomical features, making it hard to identify the exact species. Mites are arachnids, a class of eight-legged arthropods that includes spiders and scorpions.

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Dunlop received the specimen last year from Jörg Wunderlich, a German amateur arachnologist and former schoolteacher whose extensive collection is held in part by Frankfurt's Naturmuseum Senckenberg. “When he buys amber he examines it carefully for spiders, which he keeps for his own work,” Dunlop says. ”But if he finds something like a mite or a harvestmen [another group of arachnids], he often sends it to me.”

Mite of the genus Myrmozercon are still alive today. Credit: Jason Dunlop/Museum für Naturkunde, Berlin