Iberian glow-worm

Iberian glow-worm

Lampyris iberica Geisthardt, Figueira, Day & De Cock, 2008 


Although the adults may only be seen at night, the larval stage however, is easy to observe even during daytime, especially when they follow the trails of snails and slugs. The larval back is coloured velvety black with on the hind corners of each segment a lateral pale pinkish spot. 


Behaviour and where to observe 

When being a larva it is difficult to tell them apart from a close relative, Lampyris noctiluca. Adult males fly. 

Adult females are neotenic and thus show some larval-like features and lacking fully developed wings they cannot fly. This is also the case of L. noctiluca and actually all European Lampyridae. The female’s back and underside is brown, except on the ventral side where the light organ is situated; those segments have a waxy white colour. The body sides are of a pale pink colour. 

At night, in order to attract males, the female crawls out of her daytime hiding place and she poses herself stationary on the ground, on top of the leaf litter, or she might crawl up some  centimeters in the vegetation or she might even display clinging from a wall. On such “display spots” the female exposes the terminal segments of her abdomen by turning them sideways up. From these she emits a steady glow that is visibly from several tens of meters and that the males can easily locate. 


Female adult: Emits yellowish green light (~550nm) from two ventral segments and two spots on penultimate segment. The two dots are actually the larval light organs have been recuperated into the adult light organ. Sometimes, there are small parts of the light organ in the segment immediately before it, but in general it is looking like two bars and two dots of light. 

Male adult: Only bears the remnant of the larval light organ – the two glow spots – located on the ventral side of the penultimate segment. He only emits light when feeling threatened or disturbed, but he will never glow at flight. The male bioluminescence is of a similar yellowish green colour as in the females and larvae. 



Larva: The first instar (stage) can measure ± 4mm; the later instars can measure up to 30mm. Male adult: around 13 to 15 mm. Female adult: around 15 to 20 mm. 



Exists in Portugal and is abundant in the Parque Biológico de Gaia, which is one of the first places where the species was collected in Portugal. 

Ways to tell L. iberica and L. noctiluca apart L. iberica adults have a sturdier pronotum with different corners; the translucent spots on the front rim of the pronotum are more pronounced and larger in these species (note: these spots are not transparent as in Lamprohiza spp.), and they also show a paler surface around the disc of the pronotum (L. noctiluca has this equally dark-brown).The L. iberica male has clearer elytra, while L. noctiluca has totally dark wings. 

In L. iberica the thorax and abdomen are coloured dark creamed coffee brown, whereas in L. noctiluca males those body parts have a more uniform dark brown colour. Furthermore, L. iberica has clear or pink dots at the base of the pronotum. 


Text and photos - «Fireflies and Glow-worms of Portugal», 2015, ISBN n.º 978-989-98330-9-8. 


Parque Biológico de Gaia

R. Cunha, 4430-812 Avintes, Vila Nova de Gaia, Portugal


Câmara Municipal de Gaia

Rua Álvares Cabral 4400-017 Vila Nova de Gaia