In winter, potted plants are in sleep mode. This is also suspected of the pests. But if it is mild, caterpillars and Co. remain active. I too discovered eaten geraniums and begonias leaves in my pots. I went looking for the culprits and finally discovered them.
A question about the eaten leaves of the balcony plants made me take a closer look at my own window boxes in the winter quarters. And the inspection was worth it: Many leaves of the begonias and geraniums show clear, relatively large traces of eating. You can tell that they are very fresh by the fact that the edges are still green and not dried out.
Carefully examine damage caused by eating in winter quarters
Container plants spend the summer outdoors. Unobserved, insects may have looked for a home here, that is quite normal. But the very small pests such as spider mites and aphids and their eggs are more common. But with such fresh traces of food it can only be a larger roommate. The culprits could not be seen at first glance.
Eating damage is a clear indication that pests are at work. So it’s worth taking a closer look. The top and bottom of the sheet should be carefully inspected. Pests also like to hide in the ground or under leaves.

Which pest is it? This is how you look for clues
I discovered traces of excrement on the leaves. The size and shape of the droppings could also indicate mice, but these do not care much for the plant leaves. Black weevils or groundworms are among the voracious companions. The feeding tracks of the small weevil are rather narrow indentations. In this case, you are out of the question as a pest. They are also more likely to damage the roots of the tub plants if they are still stuck in the ground as a larva.
Moth caterpillars are the culprit
A look into the pot and into the ground reveals the secret. I finally discovered earthworms on the surface of the earth under dead leaves and in the upper, loose layer of soil. They are the caterpillars of owl butterflies. They are moths. Like the moths, their caterpillars are nocturnal. They avoid the light and hide in the dark, like here under the fallen leaves and in the earth.
The earthworms are very voracious and it is hard to believe how much leaf matter a very hungry caterpillar eats up. Now it is up to everyone to collect the caterpillars and offer them to the birds as food – or to eat the caterpillars and let them develop into a butterfly. I give the butterflies a chance and just leave the caterpillars in the pot, in the hope that the plant will survive the winter as a fodder plant, so to speak, and will sprout again in the spring – when the caterpillar has opened and run away as a moth.