BackArgyresthia atlanticella Rebel, 1940

Argyresthia atlanticella Rebel, 1940

Small ermine moth (English); Traça (Portuguese)

  • Kingdom: Animalia
  • Phylum: Arthropoda
  • Class: Insecta
  • Order: Lepidoptera
  • Family: Yponomeutidae
NT Near Treatened
IUCN Red List Status:

Countries of Occurrence:
Portugal - Azores


Danielczak, A.

Nunes, R. & Lamelas-Lopez, L.

Facilitators / Compilers/s:

Assessment Rationale:

Argyresthia atlanticella is an endemic species present in the islands of  Corvo, Flores, Faial, Pico, Graciosa, S. Jorge, Terceira, S. Miguel and Santa Maria (Azores, Portugal) (Borges et al. 2010). It has a large area of occupancy (AOO = 580 km²) and a very large extent of occurrence (EOO = ca 44,400 km²). This is a widespread and generalist phytophagous species, highly abundant in Azorean endemic Ericaceae shrubs. It occurs in eighteen Natural Forest Reserves, but is associated with some plants for which there are some conflicts with farmers (Erica azorica). Based on Ferreira et al. (2016) the habitat will decline as a consequence of climate change (increasing number of droughts). The species is assessed as Near Threatened (NT), since the species has an AOO of 576 km² (i.e. < 2,000 km²), and there is a continuing decline in the number of locations.

Geographic Range:

Argyresthia atlanticella is an endemic species present in the islands of  Corvo, Flores, Faial, Pico, Graciosa, S. Jorge, Terceira, S. Miguel and Santa Maria (Azores, Portugal) (Borges et al. 2010), known from several native plants of native forest. Within these islands it is known from all eighteen Natural Forest Reserves: Caldeiras Funda e Rasa and Morro Alto e Pico da Sé (Flores); Caldeira do Faial and Cabeço do Fogo  (Faial); Mistério da Prainha, Caveiro and Caiado (Pico); Pico Pinheiro and Topo (S. Jorge); Biscoito da Ferraria, Pico Galhardo, Caldeira Guilherme Moniz, Caldeira Sta. Bárbara e Mistérios Negros and Terra Brava (Terceira); Atalhada, Graminhais and Pico da Vara (S. Miguel) and Pico Alto (Sta. Maria). The extent of occurrence (EOO) is ca 44,400 km² and the maximum estimated area of occupancy (AOO) is ca 580 km².

Portugal - Azores
Extent of Occurrence (EOO):
44400 (km2)
Area of Occupancy (AOO):
580 (km2)
Elevation Lower Limit:
0 (m)
Elevation Upper Limit:
1800 (m)
Biogeographic Realms:
Endemic Azores


The species is a widespread and highly abundant species in native plants (e.g. Ericaceae, Cupressaceae and Polygonaceae) of several habitats all Azorean islands. It is probably the most common Lepidoptera species in the Azores. This species has probably a stable population.

Habitat and Ecology

Argyresthia atlanticella occurs in native forests and disturbed biotopes of several Azorean islands. According to Silva et al. (1995) and Silva and Tavares (1995), larvae are generalist polyphagous herbivores and develop on M. faya male flowers and green fruits from April until August; they were also associated with Erica azorica and Vaccinium cylindraceum, being particularly abundant in Erica azorica (Ericaceae) where larvae also develop. Adults and larvae were found associated with E. azorica throughout the year. This species has a continous development with several generations per year (multivoltine species). Altitudinal range: 0-1800 m.

Major Threat(s):

In the past, the species has probably declined due to changes in habitat size and quality, mostly the creation of pastures (Triantis et al. 2010). The main host plant Erica azorica is an early succession plant that tends to invade semi-natural pastures creating conflicts with farming Currently invasive plants Pittosporum undulatum and Hedychium gardnerianumare changing some of the areas and decreasing the quality of the habitat. These changes are decreasing the relative cover of endemic plants and changing the soil cover (decreasing the cover of bryophytes and ferns). Based on Ferreira et al. (2016) the habitat will further decline as a consequence of climate change (increasing number of droughts and habitat shifting and alteration). Since the Azores are located on the mid-Atlantic ridge, they are also prone to the effects of volcanoes and earthquakes with potential deleterious effects on the existing populations,

Conservation Actions

The species is not protected by regional law. Its habitat is in regionally protected areas (Natural Parks of Corvo, Faial, Flores, Graciosa, Pico, S. Jorge, Terceira, S. Miguel and Sta. Maria). Degraded habitats outside protected areas should be restored and a strategy needs to be developed to address the future threat by climate change. Further research is needed into its ecology and life history in order to understand its dynamics, namely at larvae stage in different endemic trees where it occurs. It is necessary a monitoring plan for the invertebrate community in the habitat in order to contribute to the conservation of this species. Monitoring every ten years using the BALA protocol will inform about habitat quality (see e.g. Gaspar et al. 2010). A taxonomic revision of Azorean Argyresthia, which should also include a comparisson of the DNA barcodes,  is needed to show how many species are present in the Azores islands.