Oak processionary moth
starts producing thousands of very small, barbed urticating hairs (ca. 0.1 mm). These hairs contain an allergenic protein, thaumetopoein; which can be actively [...] previous stage's hairs remain on the exuvia, but can become airborne and are still allergenic. In dry weather, these urticating hairs can remain allergenic [...] health risk posed to both human and animal health because they shed poisonous hairs, which can result in severe allergic reactions, amongst other health problems