What changed?

• Lanternflies fed heavily on Tree-of-Heaven, another invasive plant.

• They spread rapidly to vineyards, orchards, and hardwood forests.

• Trees weakened, leaked sap, and became more vulnerable to disease.

• Farmers faced crop losses.

• Native insects were displaced.

• Humans became part of the ecosystem response—scraping egg masses, changing land-management practices.

Big idea: One invasive insect reshaped plant health, agriculture, native species, and even human behavior.

What changed?

• Factories released soot into the air.

• Tree bark darkened; lichens died.

• Birds could easily spot light moths.

• Dark moths survived and reproduced more.

Within decades, the population evolved.

When pollution laws later cleaned the air, the trend reversed.

Big idea: Changing the environment changed which traits were favored—natural selection caught on camera.

What changed next?

• Elk overgrazed willow and aspen.

• Riverbanks eroded.

• Bird and beaver populations declined.

When wolves were reintroduced:

• Elk changed where and how they grazed.

• Vegetation recovered.

• Beavers returned.

• Rivers stabilized and even changed course.

This is a trophic cascade—a top predator reshaping the entire ecosystem.

Big idea: Removing or restoring one species can restructure land, water, and life.