In fall we watch for tree leaves to turn pretty colors—but before they turn you may see that a lot of those leaves are being chewed up! What eats tree leaves?
Although many people call leaf chewers “worms,” most aren’t worms at all! They are the early stages—called larvae—of a variety of insects.
Caterpillars are larvae that grow up to be butterflies or moths. Although many caterpillars eat plants such as milkweeds or members of the carrot family—including parsley and dill—some prefer trees!
- Inchworms (fall cankerworms) are fun to watch because they move by inching along, but they can do lots of leaf damage to many of our most popular trees, including maples, oaks, beeches, and hickories. The adults are gray moths; the males have wings, but the females are wingless!
- Catalpa worms can eat most all the leaves off catalpa trees during the summer—they become sphinx moths!
- Orangestriped oakworms strip leaves from many types of oak trees as fall approaches—they become orange moths with a white spot on each wing.
- Fall webworms are another moth caterpillar whose larvae eat the leaves of many trees— birches, cherries, crabapples, hickories, sourwoods, and walnuts—they live inside a web until they are ready to form a cocoon to become a fluffy white moth next spring.
Sawfly larvae grow up to be sawflies—they are small flying insects that lives such short lives that you may never see the adults—or mistake them for wasps if you do! The good news is they cannot sting. Their larvae can do a lot of damage to trees and shrubs, though. Dogwood sawfly larvae may “skeletonize” the leaves of many types of dogwoods, leaving just the leaf veins!
What can you do about leaf chewers?
Birds and predatory insects feed on these critters, helping manage the damage! Also, most of these leaf chewers do their eating late enough in the year that the trees will soon drop their leaves anyway, so most don’t suffer any serious harm.
- Catalpa worms eat a bit earlier in the summer, though, and if you love to fish, you can help save tree leaves by collecting these chewers to use as bait!
- You can stop fall webworm damage by disturbing the web—get an adult to help you cut off any of the webbed areas, use a stick to tear up the web, or use a strong stream of water from a garden hose to bust up the web!
- Some years fall cankerworms can eat almost all the tree leaves, producing a lot of droppings— their swinging down on spiderweb-like strands bothers some people, too! You can ask an adult to help you trap the new female moths as they crawl up the trees later this fall, once the leaves have dropped and we’ve had a freeze. The City of Charlotte has instructions for how to make sticky band traps: https://charlottenc.gov/Engineering/LandscapeManagement/Trees/Documents/CankerwormBrochure2017.pdf#search=fall%20cankerworm
Article by Debbie Green, Extension Master GardenerSM Volunteer
For More Information:
Inchworms (fall cankerworm):