We recently received this message from a reader, “I have not had Catawba worms on my trees for 5 years. Is there anything I can do to get them back?” Before we speculate on why our reader’s tree is worm-less, we will provide some background information on catawba worms!
Catawba worms, or Catalpa worms (Catawba and Catalpa are interchangeable words), are actually caterpillars not worms. They are the larvae of the sphinx moth. Catawba worms and Catawba trees (or Catalpa trees), have a mutually beneficial relationship. The foliage of a Catawba tree is the only food source for the Catawba worms, so the caterpillars need the trees to eat and survive. On the other hand, the dung of the Catawba worms fertilizes the soil around the tree to help it grow and stay healthy, so the trees need the caterpillars!
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The relationship between Catawba trees and Catawba worms is well known. Some people even plant Catawba trees in the hopes that the trees will attract Catawba worms. Catawba worms are a popular choice for fishing bait, so many people plant the trees to have easy access to bait.
So, why are there no Catawba worms on our reader’s Catawba trees? We don’t know for sure, but we can provide some potential answers. First, Catawba worms only eat the foliage of healthy Catawba trees. Perhaps her trees are declining in health and are no longer appetizing to the caterpillars. Also, Catawba worms emerge based on weather patterns. It is possible that the climate has shifted and now her trees are unsuitable for the Catawba worms. Finally, like all creatures, Catawba worms have natural predators. If the caterpillar population was wiped out one year by a predator, that could explain why there are no more Catawba worms. We aren’t aware of any guaranteed ways to get the caterpillars back.
To summarize, a reader wants to know why there are no Catawba worms on her Catawba trees. We have provided a few potential answers, but if other readers have ideas about these caterpillars we encourage them to share them below!
All About Worms is always free, always reader-supported, we don't subject you to ads or annoying video pop-ups. But it does cost us money out of our pocket to keep the site going (nearly 20 years so far!) So your tips via CashApp, Venmo, or Paypal are appreciated! Receipts will come from ISIPP Publishing.
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I know why at least I’m my case . Always found worms on scraggly none fertilized trees out in fields. I got some seeds planted some and got 2 trees to plant planted them in desired spot and had abundance of worms for 6 years. Then I got the bright idea to fertilize and haven’t had a worm since I did that. Trees took off grew wonderfully. But after that initial fertilizing mistake ( I realized in a couple months and no worms) I never fertilized again and that was 10 years ago and still no worms. I’ve about figured ,for sure, that if I want to go for worms again collect more seeds , grow more trees and find a long non fertilized spot to plant them and never fertilize again. I don’t know if that goes for all fertilizer but that that I use, commercial, around my fruit trees in spring is what i am positive the culprit. But the trees in pastures fertilized with chicken manure I think I still see worms. So if you want a pretty tree fertilize. But if you want worms keep it scraggly and don’t repeat my mistake of fertilizing to make a big tall green worm tree, that doesn’t work. So I’ll shovel prune ( chainsaw) and start over.