- The author describes Berlin's hottest day and an infestation of oak processionary caterpillars (Eichenprozessionsspinner) with toxic hairs that cause severe itching and rashes.
- Caterpillar hairs can become airborne, travel far, survive for years, and penetrate clothing, causing painful stings and potential eye or respiratory issues.
- Climate change, particularly warmer and sunnier springs, has led to mass outbreaks of these caterpillars across Europe, including Germany, Britain, Denmark, Netherlands, and France.
- Efforts to control the caterpillars—such as vacuuming, pesticides, and nematodes—have limited effectiveness, and experts suggest humans must adapt to their presence.
- The caterpillars have a long evolutionary history and are found worldwide, but human carbon emissions may worsen outbreaks, highlighting our own role in the ecological crisis.