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Oriental Moth

Monema flavescens (formerly Cnidocampa flavescens)[3]

The oriental moth is an Asian slug moth whose brightly colored caterpillars, called stinging nettle caterpillars, carry spines that sting like nettles.[1][2]

Group
Insect
Order
Lepidoptera
Family
Limacodidae
US records
1 state
Sources
3 cited
Updated
2026-10-17
Oriental moth caterpillar, green and yellow with spiny horns, on a leaf
Oriental moth caterpillar, green and yellow with spiny horns, on a leaf. (c) Teá Montagna, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0
On this page
  1. Identification
  2. Where it lives
  3. Biology
  4. Damage and signs
  5. Health risk
  6. Control
  7. Related profiles
  8. Common questions
  9. Sources

How to identify it

  • Caterpillars are green and yellow with blue, green and purple markings and fleshy horns bearing stinging spines; grown larvae are 18 to 24 mm long.[1][2]
  • Mature caterpillars spin hard, white and gray-brown cocoons in the forks of small twigs, where they can pass for buds.[1][2]
  • Adults are brownish moths about 30 mm long.[2]

Where it lives

Native to East Asia; in the US it is known only from Massachusetts, where cocoons likely arrived in a Boston suburb around 1906, and it is now rarely seen within about 30 miles of Boston.[1][2]

US map: public records from 1 state since 1990 (GBIF).

Biology and life cycle

It spends the winter in its cocoon; in Massachusetts adults emerge from late June to early August and lay flat, transparent eggs singly under leaves.[1]

Caterpillars feed from late July into October, first on leaf undersides, later eating whole leaves down to the midrib, through six to eight larval stages.[1][2]

In Asia there are one or two generations a year, depending on climate.[2]

Damage and signs

  • In Massachusetts it feeds on many hardwoods, mostly Norway maple, sycamore maple, apple and hawthorn.[1]
  • In Asia it is a growing pest of fruit, nut and urban trees, but Massachusetts populations are so low that they cause no measurable damage.[1][2]

Health risk

The caterpillars' spines cause a nettle-like irritation on skin, so they should not be handled.[1][2]

Control

Biological control

Parasitoids released near Boston from China and Japan between 1917 and 1930 attacked it, though it is unclear whether they persist.[1]

Pesticides

Chemical treatment is almost certainly unnecessary because populations are too low to cause measurable damage.[1]

When to call a professional

In Massachusetts, photograph any caterpillar you find and report it to the Department of Agricultural Resources (MDAR); MDAR or UMass Extension can help send a sample to USDA APHIS for confirmation.[1]

Common questions

Is the stinging nettle caterpillar dangerous?
Its spines sting like nettles, so don't touch it; it is rarely seen.[1][2]
Where are oriental moths found in the US?
Only in eastern Massachusetts, mostly around Boston.[1][2]

Sources

  1. UMass Extension Landscape, Nursery and Urban Forestry Program (Landscape Insect & Mite Guide), “Monema (Cnidocampa) flavescens (Oriental Moth, Stinging Nettle Caterpillar).” www.umass.edu/agriculture-food-environment/landscape/publications-resources/insect-mite-guide/monema-cnidocampa-flavescens (accessed 2026-10-16)
  2. European and Mediterranean Plant Protection Organization (EPPO), “EPPO Alert List: Monema flavescens (Lepidoptera: Limacodidae).” www.eppo.int/ACTIVITIES/plant_quarantine/alert_list_insects/monema_flavescens (accessed 2026-10-16)
  3. iNaturalist, “Monema flavescens taxon page (order and family).” www.inaturalist.org/taxa/484293 (accessed 2026-10-06)

Updated 2026-10-17. Built from sourced records. Spot an error? Tell us.