Oak Trees Delay Leaf Growth to Reduce Caterpillar Damage

Thu, 07 May 2026 05:48:00 +0200

Recent research from the University of Würzburg has revealed a surprising defensive strategy used by oak trees. When oak trees experience heavy caterpillar infestations in one year, they delay leaf growth by roughly three days the following spring. This slight postponement prevents newly hatched caterpillars from accessing tender leaves, significantly reducing their survival and cutting leaf damage by more than 50 percent. Unlike chemical defenses, such as producing bitter tannins, this timing adjustment is energy-efficient and highly effective. Using a combination of ecological field studies and radar data from Sentinel-1 satellites, the research team monitored over 2,400 square kilometers in Northern Bavaria from 2017 to 2021. The approach allowed them to track which trees were heavily attacked and how they adjusted in the following year. This discovery suggests that tree phenology is not solely temperature-driven but also shaped by biological threats like herbivorous insects. The fi