Black arches

The moths of Lymantria monacha have a wingspan of 40 to 50 mm. They have white forewings with black connected wavy arches which gives the moth its name. The light brown hindwings have white fringes having black spots. They also have a characteristic biscuit-coloured abdomen with a black band. Females are larger and have elongated wings.[1]

The eggs are oval, light brown or light red. Larvae are whitish grey to blackish, with grey hairs, red and blue warts, and a dark longitudinal dorsal line which is interrupted or broadened into spots in places. Pupa is golden glossy red-brown or dark brown, with reddish hairs dorsally and rather long anal point.[1]

White forewing with black basal spots and four sharply angulate black transverse lines, the second of which is the broadest; hindwing greyish white and grey. Abdomen light rosepink. The species varies strongly and has received the following aberrational names, nigra Fr.: The two central bands are confluent at the costal and posterior margins, forming black spots, or the whole median area is dark, the red of the abdomen usually weaker, eremita G.: Forewing and abdomen smoke-brown or blackish grey, the former with black markings, atra Linst.: Forewing uniformly black, without markings, hindwing greyish brown, abdomen black, lutea Anel is a light form in which the central bands are interrupted; the red colour of the abdomen is equally deep almost to the thorax, flavoabdominalis Schultz has the abdomen yellow instead of red; subfusca Schultz female is distinguished by everything which is black in true monacha being yellowish brown, and the abdomen being also yellowish brown instead of red; in obsoleta Schultz the dark transverse bands in the median area of the forewing are absent, while they remain in the basal and outer-marginal areas. All these names were given to European specimens.[3]

This moth can be found in most of Europe, including Great Britain, and in temperate regions of the Palearctic East to Japan and India.[1][4]

The larvae hibernate when young, remain together in batches and are fullgrown in June.

• 
  ♀
• 
  ♂

• 
  Illustration from The Moths of the British Isles
• 
  Caterpillar
• 
  Pupa
• 
  Pheromone trap for Lymantria monacha

• Forest protection
• Lepidoptera
• Lymantriidae

• Carter, David (1992) Butterflies and Moths. Dorling Kindersley Handbooks, London. ISBN 0-7513-2707-7.

Wikimedia Commons has media related to Lymantria monacha.

• Black arches on UKmoths
• Lepiforum.de
• Invasive Species Compendium - Lymantria monacha, CAB International
• Species Profile - Nun Moth (Lymantria monacha), National Invasive Species Information Center, United States National Agricultural Library