Stick Caterpillar 尺蛾幼蟲 尺蠖

In the last few days, noticed caterpillar like droppings sometimes on balcony rail or floor, quite dark & hard, like charcoal 焦黑. Not sure if they were pollutants or droppings. Early morning, still partially dark, looking out from inside, saw a worm shape spanning two branches, definitely not twigs. Looked closer, saw some leaves nearby chewed partially.

After seeing Miyuki off to work, came back, looked closer when brighter. It disappeared. Later found it! Its digestive system clearly more advanced than that of butterfly caterpillars as it appears to have processed the leaves more thoroughly.

The stick caterpillar is the larval form of the peppered moth (​Biston betularia​). The stick caterpillar looks like bark and twigs, hence its nickname, and it mimics twigs in multiple ways to hide from predators.

Usually more common up north, is it because of climate change?

Post Notes: similar to local 大鉤翅尺蛾_柑桔尺蛾?