Streetlit hedgerows can have fewer moth caterpillars. What hidden step may explain it?

Answer: Fewer eggs laid there

Leaves turn poisonous — Almost, but too strong. Artificial light can change plant-insect interactions, but the hedgerow result does not require leaves to become poisonous. The study measured fewer caterpillars under streetlights and discussed several possible mechanisms. Plant quality can be a bottom-up effect in some systems, while egg-laying behavior is a direct reproductive step. The safer answer is that lit habitat may receive fewer eggs in the first place.

Fewer eggs laid there ✓ — Correct. The obvious guess is that adult moths simply die at the light, but roadside studies found fewer caterpillars in lit habitats too. Researchers suggest disrupted activity and reduced egg-laying in illuminated areas as one important mechanism, with predation and plant effects also possible. One southern England study reported up to 52 percent fewer moth caterpillars under LED street lamps in hedgerows. The real lesson is that light can damage a life cycle before an insect ever reaches the lamp.

Adults forget wings — No. Adult insects do not literally forget how wings work. Artificial light can disrupt flight orientation, mating, feeding, and timing, which is already enough to affect populations. The caterpillar result is especially interesting because larvae are counted in the habitat, not just adults at a lamp. That points to life-cycle effects such as where adults choose to lay eggs and how larvae develop.