Nun moth

Insect type
  • Order: Lepidoptera
  • Family: Lymantriidae
  • Latin: Lymantria monacha 
  • English: Nun moth
  • French: La nonne


This species is not found in Canada

Diet and feeding behavior

Phytophagous / Phyllophagous / Free-living defoliator



Damage, symptoms and biology

Lymantria monacha produces one generation per year. Adults emerge from late July to early September; males fly to locate females, which lay eggs, from 20 to 300, in crevices of host bark and under bark scales of conifers, primarily on the lower 3.65 m (12 feet) of the trunk. Females may fly after depositing most eggs. The eggs overwinter, and larvae begin hatching at the beginning of May, and may continue to hatch, depending on the temperature, until July. Larval hatching usually coincides with bud break. Larvae eat new foliage initially, and older foliage in later stages. Young larvae can be carried by wind. They may have 5 or 6 instars. When at rest, the larvae congregate in sheltered locations. Pupae occur in July and August, usually inside light silken cocoons in crevices of the bark. Both male and female adults are good fliers, they are active at night and are attracted to lights. The males can be captured in pheromone traps. In the Far East of Russia, L. monacha's activity peak is between 03:00 and 05:00 hours.

Inspectors should look for clusters of naked eggs in bark crevices of nursery trees, on logs, forest products, sea containers and ships.


Egg: Purplish and spheroid with a raised pattern. Larva: Grows to 30-35 mm. Head is pale brown with dense black markings. Body is greyish yellow to yellow, with black hair tufts and a black dorsal band. Numerous black and white secondary setae (hairs) are present, mainly short, except those on prothoracic and anal segments. Each abdominal segment from 1 to 4 has a dorsal pair of small, reddish, glandular protrusions; segments 6 and 7 have prominent mid-dorsal, reddish glandular warts. Pupa: Naked, stout, reddish brown, with tufts of reddish brown setae; posterior tip elongate, longitudinally lined, terminating in many stout, hooked setae, 18-20 mm long. Adult: The forewing is white, with black spots and wavy lines with sharp points; the hindwing is greyish brown, minute hairs on edge white with brown spots. The head is white; thorax white marked with black; abdomen pink with brown transverse bands, more distinct in female; antennae of male feather-like, of female weakly so. A melanic grey-brown form of the male is also known to occur. Male wing span >41 mm . Female wing span >53 mm.

Other resources

Information on host(s)

Main Host(s)

Apples, birch, cherries / plums, firs, larches / tamaracks, maple, oaks, pines, spruces

  • Lymantria monacha


  • Lymantria monacha

    Young caterpillar

  • Lymantria monacha

    Female and male (black morph)

  • Lymantria monacha


  • Lymantria monacha

    Pupal exuviae

  • Lymantria monacha

    Total defoliation

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