Germany's Parks Are Closed. The Heat Is Record-Breaking. The Culprit Is a Caterpillar.

Berlin authorities have closed shady public green spaces as residents seek relief from record-breaking heat — not because the parks are dangerous from the heat, but because the shade trees are. Responsible is a small caterpillar equipped with roughly 600,000 microscopic barbed hairs that deliver hives, rashes, respiratory distress and, at worst, anaphylactic shock. They're called oak processionary caterpillars, and they colonize the oak trees Berliners depend on for shade.

Playground equipment — swings, slides, roundabouts — is roped off behind red-and-white barrier tape. The setup is a genuine lose-lose. Temperatures hit 107 degrees Fahrenheit (42 degrees Celsius) over the weekend, driving residents out of apartments that, like most in Germany, have no air conditioning. The park is where you go to survive. Except the park is closed.

What makes the oak processionary caterpillar particularly alarming is the delivery mechanism. Its microscopic, barbed hairs carry a toxin that causes rashes, conjunctivitis and breathing difficulties. The hairs break easily and can travel long distances on the wind. You don't have to touch one. You just have to be nearby when the breeze picks up. Authorities now advise against opening windows.

Oak processionary caterpillars aren't new to Germany, but their numbers are climbing with the temperature — expanding across the city faster than pest control teams can respond. Berlin's city government is actively at odds over who is responsible for clearing the nests, a question that matters because removal is costly: hazmat-suited teams with specialized vacuums, one of which reportedly spent an entire day clearing a single tree containing 800 nests. A city official acknowledged there is no way to eradicate the problem. The goal now is damage limitation.

Eight hundred nests. One tree. One day. The caterpillar is not losing this fight.

Read the full story at NPR, June 30, 2026

Hot Take: A creature the size of a thumb has shut down the parks of a major European capital during a heat emergency, and the city's official response is a jurisdictional dispute about who owns the vacuum. The oak processionary caterpillar did not come to negotiate.