Notas / Notes


Forums and social media help to discover exotic species in Europe and monitor their spread: the case of Exaireta spinigera (Wiedemann, 1830) (Diptera, Stratiomyidae) in the Italian peninsula and Sicily

Enrico Schifani1,* & Ronni Paolinelli2

1Section Animal Biology, Department STEBICEF, University of Palermo. Via Archirafi 18, I - 90123, Palermo, Italy. ORCID iD:

2Via Ranzini 3, I-27018, Vidigulfo (PV), Italy. ORCID iD:

*Corresponding author:



The soldier fly Exaireta spinigera (Wiedemann, 1830) (Diptera, Stratiomyidae) is native to Australia and has been introduced in Hawaii, North America and is quickly spreading across Europe. We comment the existing knowledge concerning its presence in Italy and publish the first records from Sicily. The existing knowledge regarding arrival and distribution of this species in Italy is exclusively based on data provided by citizens through biodiversity-focused internet forums and Facebook groups, which have hence proved to be a useful aid to the difficult detection of invasive species.

Key words: Diptera; Stratiomyidae; citizen science; Facebook; invasive species; biodiversity data.



Los foros y las redes sociales ayudan a descubrir especies exóticas en Europa y monitorear su propagación: el caso de Exaireta spinigera (Wiedemann, 1830) (Diptera, Stratiomyidae) en la península italiana y Sicilia

La mosca soldado Exaireta spinigera (Wiedemann, 1830) (Diptera, Stratiomyidae) es originaria de Australia y se introdujo en Hawái, América del Norte y se está extendiendo rápidamente por Europa. Comentamos el conocimiento sobre su presencia en Italia y publicamos los primeros registros de Sicilia. El conocimiento existente sobre la llegada y distribución de esta especie en Italia se fundamenta exclusivamente en datos proporcionados por ciudadanos a través de foros de internet y grupos de Facebook sobre biodiversidad, que así han demostrado ser una ayuda útil para la difícil detección de especies invasoras.

Palabras clave: Diptera; Stratiomyidae; ciencia ciudadana; especies introducidas; especies invasoras; biodiversidad.


Recibido/Received: 24/06/2018; Aceptado/Accepted: 21/09/2018; Publicado en línea/Published online: 22/10/2018

Cómo citar este artículo/Citation: Schifani, E. & Paolinelli, R. 2018. Forums and social media help to discover exotic species in Europe and monitor their spread: the case of Exaireta spinigera (Wiedemann, 1830) (Diptera, Stratiomyidae) in the Italian peninsula and Sicily. Graellsia, 74(2): e079.

Copyright: © 2018 SAM & CSIC. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) License.



The garden soldier fly Exaireta spinigera (Wiedemann, 1830) is an Australian member of the family Stratiomyidae Latreille, 1802. It is the second exotic species of this family to arrive in Italy after Hermetia illucens (Linnaeus, 1758), which was first recorded in 1956 (Venturi, 1956). Outside its native range, E. spinigera is known in Hawaii (Hardy, 1960), North America (Swann et al., 2006), France (Lapeyre & Dauphin, 2008) and Italy (Cocquempot & Martinez, 2017). Its status as exotic species in New Zealand is currently uncertain (Derraik & Heath, 2009). Despite the broad distribution achieved, the interactions of E. spinigera within non-native ecosystems as well as its general biology are mostly unknown. Its traits may be generally similar to those of the relatively well-studied H. illucens (Cocquempot & Martinez, 2017), which is not usually regarded as a pest species or a threat to native ecosystems. However, even the impacts of H. illucens on native biodiversity are also mostly uninvestigated (De Groot & Veenvliet, 2011).

The presence of E. spinigera was first recorded in Italy from the Italian peninsula by Cocquempot & Martinez (2017), who cited an observation originally appeared on the Italian internet forum ‘Forum Natura Mediterraneo – Forum Naturalistico’. We attempted to find additional E. spinigera observations by searching in Italian Facebook groups and internet forums with a focus on terrestrial faunistic biodiversity (Table 1). As a result, nine additional records were found among Facebook groups and internet forums (Table 1), revealing the presence of this exotic species in the island of Sicily.

Table 1.— Facebook groups and internet forums consulted during the research (only groups with > 1,000 users are listed).
Tabla 1.— Grupos Facebook y foros de internet italianos que fueron consultados durante el transcurso de esta investigación (solo grupos con > 1.000 usuarios estan listados).
Name Type Link N° of users (June 2018) Main topic Observations of E. spinigera
Insetti e altri artropodi- un fantastico mondo da scoprire Facebook group (public) 22,170 Italian insects and arthropods 1 individual, no locality or date, uploaded in 2016
1 individual, Gioiosa Marea (ME), Sicily, Italy, May 2017
1 individual, Catania (CT), Sicily, Italy, 2 Jul 2018
Fauna Siciliana Facebook group (closed) 17,420 Sicilian terrestrial and freshwater fauna 1 individual, Giarre (ME), Sicily, Italy, April 2018
1 individual, Gioiosa Marea (ME), Sicily, Italy, July 2018
Forum Natura Mediterraneo – Forum Naturalistico Internet forum 15,370 Italian biodiversity 1 individual, Acquapendente (VT), Italy, 2015.
1 individual, Acquapendente (VT), Italy, 2016 (reported in Cocquempot & Martinez 2017).
Birdwatching & Wildlife Facebook group (closed) 13,300 Photography of Italian fauna (mostly birds) None
Riconoscimento insetti Facebook group (public) 10,120 Identification of the Italian entomofauna 1 individual, no locality or date, uploaded in 2017
1 individual, Acireale (CT), Sicily, Italy, 16 Sept 2018
Fotografare insetti e fiori Facebook group (public) 9,425 Photography of flowers and Italian entomofauna None (a single case of misidentification of Sargus sp.)
IDENTIFICAZIONE ANFIBI E RETTILI Facebook group (public) 8,630 Identification of Italian herpetofauna None
ENTOMOLOGIA Facebook group (public) 6,640 Italian entomofauna None
Forum Entomologi Italiani Internet forum 6,190 Italian entomofauna None
Aracnofili, allevatori e studiosi di ragni Facebook group (public) 5,450 Italian and exotic spiders None
Flora e fauna della Sardegna e non solo Facebook group (public) 5,110 Sardinian fauna and flora None
Aracnofilia Forum Internet forum 4,656 Captive breeding of Arachnida None
Entoforum Internet forum 2,140 Captive breeding of exotic insects None Internet forum 1,990 Captive breeding of Italian ants None
Libellule d’Italia Facebook group (public) 1,750 Italian Odonata None

Containment or eradication of invasive exotic species can be virtually impossible or at least very costly if their presence is not detected early enough after their first arrival. Therefore, the development of early-warning systems in Europe is a crucial need (Genovesi, 2005). Many citizen science projects have obtained valuable results in the aim of collecting distribution data on exotic species, including in Europe (e.g., Bois et al., 2011; Zenetos et al., 2013; Adrianes et al., 2015; Maistrello et al., 2016, 2018; Mori et al., 2017) and more specifically in Sicily (e.g., Faraone et al., 2017; Mannino & Balistreri, 2018). The involvement of a large number of citizens can be a precious tool in order to monitor species presence across large areas. Exaireta spinigera is a relatively large insect (up to about 14 mm) and it is characterized by a colorful and easily distinguishable habitus (Fig. 1). It may easily attract the attention of a potential photographer and it can be identified even with a low-quality picture due to its unmistakable aspect. Significant occurrence data on Diptera, gathered from pictures taken by non-specialists and uploaded on internet, were also gathered in the case of native and even endangered species (e.g., Marcos García & Ricarte, 2013; Álvarez Fidalgo et al., 2018). The presence of E. spinigera in the Italian territory (peninsular Italy and now Sicily island) is solely known thanks to amateur entomologists and other citizens, who operated outside the framework of a focused citizen science project, but were active in biodiversity-themed internet forums and Facebook groups. In these forums and groups hundreds of thousands of relatively verifiable data are uploaded daily, mostly following a very simple but effective ‘protocol’: providing pictures of organisms along with temporal and geographic information. Such protocol is the same of platforms as iNaturalist ( While the resulting data may be comparatively less easily available to the scientific community in the case of forums and Facebook groups, social media may attract more participants. In conclusion, a way to easily pass the data uploaded on social media and forums to large databases like GBIF (Global Biodiversity Information Facility, could be beneficial in the future. The use of social media to gather relevant data on biological and ecological issues is likely to increase in the future (e.g. Hart et al., 2018).

Fig. 1.Exaireta spinigera in Sidney, Australia. Photo by John Tann.
Fig. 1.— Exaireta spinigera en Sídney, Australia. Fotografía de John Tann.




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