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Garden Q&A: How to handle bagworm outbreaks

Bagworm cases are easiest to see on bare branches.

Q: A few of our shrubs had outbreaks of bagworms last year. I see a few still hanging on the bare branches and evergreen stems. How can I tell if they’re dead?

A: Older bags from prior years that you might not have noticed before will have a more weathered, paler look, but in general they’ll look the same whether alive and hibernating or dead or empty. Bags with an old papery brown pupal case sticking out of the bottom are empty, but those fragments can shred and disappear in the wind over time, so might not be a reliable way to tell them apart.

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Assume they are alive and pull or clip off those you can reach. Bagworms spend the winter as eggs tucked within the shelter of the bag, so if you can remove them before they hatch around May, you’ll knock out a substantial amount of the population before they can disperse. The tiny bags of very young bagworm caterpillars can be very hard to find, and you don’t want to wait until they’re older and the bags are bigger to deal with them later. More life cycle information and options for management can be found on our Bagworms on Trees and Shrubs page.

Q: If our trees and shrubs suffer from ice or winter storm breakage, is there anything we can do about it to help them heal?

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A: Usually broken branches are best pruned off with a clean cut so they seal over as quickly and smoothly as possible. More rarely, you might get lucky and can get the split ends to graft themselves back together if you realign the jagged ends and bind the site well to keep it from drying out, an approach not too different from grafting for propagation. A sturdy support structure of some sort will be needed to support the branch’s weight until it reattaches. If the exposed sapwood dehydrates too much, though, the attempt probably won’t work; plus, some species are also probably easier to repair in this way than others.

In general, I would assume a broken branch is not salvageable and arrange to prune it off as soon as the weather allows. Remember that cuts should not be made flush with the trunk (or nearest larger branch) because this will prevent the wound from closing properly. Visit our Pruning Trees page for more information about how to make a proper pruning cut. Trees or any large limbs that are too hard to reach from the ground or using conventional pruning tools like a folding saw or pole pruner should be left to the professionals.

University of Maryland Extension’s Home and Garden Information Center offers free gardening and pest information at extension.umd.edu/hgic. Click “Ask Extension” to send questions and photos.


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