K. gracilis has been shown to reduce survival on saplings, but adult trees have been found with more than 30 feeding scars on their roots.

But trees that are weakened by air pollution or changes in soil chemistry may invite K. gracilis infestation.

They are cryptically colored, but are active for 20–40 minutes each dawn and twilight, and occasionally come to light.

It takes two years for the larvae to mature, so populations tend towards two-year cycles.

Females emit pheromones to attract males, from organs on their hind wings.