Have you noticed skeletonized leaves on your tree or shrub?
The Redhumped Caterpillar is the culprit. It is seen on Eastern and Western Redbud trees, which seem to be their favorite food. But they will also eat Willow, Cottonwood, Liquidambar, Cherry and Plum trees, as well as other deciduous trees and shrubs.
These caterpillars eat the leaves except for the tough veins. Usually the caterpillars are easy to find because they stick close to each other.
But, don't worry, it usually doesn't do a huge amount of damage and is pretty simple to deal with.
The caterpillars hatch out of eggs that the gray moths lay under leaves of their favorite food plants. When they hatch out in the summer, they start eating leaves and growing.The caterpillars start out 1/8" long and grow to be about 1 1/2".
These caterpillars are slow moving and stay close together as they eat making them easy to spot and control.
Usually, cutting off the branch they are on and disposing of it in the green waste bin is all you need to do to control these pests.
Most trees and shrubs suffer only minor setbacks when Redhumped Caterpillars move in. Keeping the plant vigorous by managing irrigation and providing mulch will help it recover quickly.
Sometimes a tree is suffering too much damage and you may want to take more decisive action. If your tree is losing more than 30% of it's leaves, it is probably time to try a narrow range pesticide such as Bt.
Bt is a pesticide that only affects caterpillars of moths and butterflies. It must contact eating caterpillars and will take several days to affect them. Just treat the plant with caterpillars so that the butterflies we love are not killed also. You can probably get Bt at your local nursery.
Get expert help if you are worried about pests.
University of California Integrated Pest management has resources for you to identify the least toxic and narrowest acting treatments. This helps keep you, your landscape, and the environment safer. Here is their Redhumped caterpillar page.
The Placer County Master Gardeners are trained to answer gardening questions. Give them a call, (530) 889-7388, or email them from their website.