This caterpillar is eating my crabapple leaves. It has a dark body with greenish-yellow striping, a black head and orange neck collar. It turns upside when disturbed, showing its orange underside. What kind of caterpillar is it? (Northampton County, PA, USA)
They are the Yellow-necked caterpillar.
These are found in eastern North America. It is not known if the moth feeds…many moths do not.
The larvae feed on leaves of deciduous trees and shrubs and may be pests. I have had them on my apples and birch trees.
When you disturb them they curl the head and tail together to try and scare you away. They do move and feed in groups and can defoliate a large section of a tree. But do not kill the tree.
You can try to shake them off…many may be eaten by birds, some may find their way back on the tree but most will not. You can step on them when they land on the ground after shaking the tree.
If all that fails, the bacterial insecticide Bt controls caterpillars of moths and butterflies. Consult the label before spraying.