Pest profile

Catalpa Sphinx

Ceratomia catalpae · Lepidoptera: Sphingidae[2]

Catalpa worms are native caterpillars that may defoliate catalpa trees in outbreak years, but control is often not warranted.[1]

Catalpa worm, a black-backed caterpillar with yellow sides and a black tail horn, on a catalpa leaf
Catalpa worm, a black-backed caterpillar with yellow sides and a black tail horn, on a catalpa leaf. (c) Matt Berger, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • Older caterpillars vary from yellow to nearly black, most black on the back with a broad yellow side stripe and a long straight black horn.[1]
  • Adults are large brown sphinx moths with a gray, black-rimmed spot on each forewing and no yellow abdominal spots.[1]

Look-alikes

Look-alikeHow to tell them apart
Tomato hornwormIts similarly colored adult has yellow spots on the abdomen; the catalpa sphinx doesn't.[1]

Where it lives

Native to the eastern US, it occurs wherever catalpa grows from New Hampshire and Nebraska south to Florida and Texas.[1]

US map: public records from 29 states since 1990 (GBIF).

Biology and life cycle

Pupae overwinter in soil; moths fly April to October and lay masses of 100 to 1,000 eggs under leaves.[1]

There's one generation in Pennsylvania and up to five farther south; outbreaks come and go over a few years.[1]

Damage and signs

  • Caterpillars feed only on catalpa; healthy trees survive complete defoliation and often releaf.[1]
  • Repeated outbreaks can kill trees already weakened by stress or disease.[1]

Health risk

It feeds on plants; Penn State Extension mentions no risk to people.[1]

Control

Prevention

Keep trees healthy with proper water and fertilizer so they tolerate defoliation.[1]

Traps and physical control

Remove egg masses, trim out young groups, or hand-pick caterpillars into soapy water on small trees.[1]

Biological control

Parasitoid wasps, especially Cotesia, often control them; leave caterpillars covered in white cocoons on the tree.[1]

Common questions

What are the black and yellow caterpillars eating my catalpa?
They're catalpa worms, the only sphinx moth caterpillars that feed on catalpa.[1]
Will catalpa worms kill my tree?
Healthy trees withstand complete defoliation; repeated outbreaks mainly threaten stressed trees.[1]

Sources

  1. Penn State Extension, “Catalpa Worm/Catalpa Sphinx Moth.” extension.psu.edu/catalpa-worm-catalpa-sphinx-moth (accessed 2026-10-06)
  2. iNaturalist, “Ceratomia catalpae taxon page (order and family).” www.inaturalist.org/taxa/143440 (accessed 2026-10-06)

Updated 2026-10-14. Built from sourced records. Spot an error? Tell us.