Introduction

The superorder Neuropterida comprises about 6500 extant valid species worldwide, distributed across three orders, Neuroptera (“lacewings”), Megaloptera (“alderflies”), and Raphidioptera (“snakeflies”), with sixteen, two, and two extant families respectively. Neuropterida fossils have recently been discovered in southern Switzerland in the Kalkschieferzone of the Meride Limestone (Middle Triassic, Ladinian) of Monte San Giorgio (UNESCO World Heritage List), but these are still undescribed and unnamed.

Geographical and Geopolitical Divisions of Switzerland

Switzerland is a small landlocked country in the heart of Europe. It is divided politically into 26 cantons (Fig. 1), whose areas differ substantially in size, from 37 to 7105 km2 (Table 1), and in relief (Fig. 2). The extreme vertical elevation difference found within the country – from 200 m at Lake Maggiore in the south to 4600 m in the Alps – provides a wide diversity of habitats for neuropterid insects. Significantly, Switzerland spans the Alps and contains both northern temperate and southern Mediterranean faunal and floral elements.

Figure 1. Cantons of Switzerland.
Table 1. Cantons of Switzerland.
Canton
(English Name)
Canton
(Local Name)
Abbreviation Area (km2) Area (%)
Aargau Aargau AG 1404 3.4
Appenzell Ausserrhoden Appenzell Ausserrhoden AR 243 0.6
Appenzell Innerrhoden Appenzell Innerrhoden AI 173 0.4
Basel-Landschaft (rural) Basel-Landschaft BL 518 1.3
Basel-Stadt (city) Basel-Stadt BS 37 0.1
Berne Berne BE 5959 14.4
Fribourg Fribourg FR 1670 4.0
Geneva Genève GE 282 0.7
Glarus Glarus GL 685 1.7
Grisons Graubünden GR 7105 17.2
Jura Jura JU 839 2.0
Lucerne Luzern LU 1493 3.6
Neuchâtel Neuchâtel NE 803 1.9
Nidwalden Nidwalden NW 276 0.7
Obwalden Obwalden OW 491 1.2
Schaffhausen Schaffhausen SH 298 0.7
Schwyz Schwyz SZ 907 2.2
Solothurn Solothurn SO 790 1.9
St. Gallen St. Gallen SG 2026 4.9
Thurgau Thurgau TG 991 2.4
Ticino Ticino TI 2812 6.8
Uri Uri UR 1077 2.6
Valais Valais VS 5224 12.7
Vaud Vaud VD 3212 7.8
Zug Zug ZG 239 0.6
Zürich Zürich ZH 1729 4.2
Switzerland Switzerland CH 41283 100.0

Neuropterida of Switzerland

The Swiss Neuropterida fauna contains approximately 15% of the species presently known from the western Palearctic (sensu H. Aspöck et al. 2001). Current counts of the numbers of valid species of the superorder Neuropterida (and its orders) that are known from Switzerland (and its cantons) are given in Table 2. These numbers have continued to climb in recent years through the documentation of newly discovered and described taxa, including new cryptic species revealed using modern morphological and molecular techniques. One species, Acanthaclisis occitanica, is known only from historical records, and is currently regarded as extinct within Switzerland. The Raphidioptera are represented by two families: Raphidiidae and Inocelliidae; the Megaloptera by one family: Sialidae; and the Neuroptera by seven families: Chrysopidae, Coniopterygidae, Hemerobiidae, Mantispidae, Myrmeleontidae, Osmylidae, and Sisyridae.

Switzerland shares all of its major biomes with other surrounding countries – Austria, France, Germany, Italy, and Liechtenstein – so it contains no endemic neuropterid species, and many small cantons have few recorded Neuropterida (unless they happened to have been home to an active neuropterologist; e.g. Willy Eglin in Basel-Stadt).

Post-Glacial Development of the Swiss Neuropterida Fauna

The present vegetation and fauna of Switzerland depend very much on the catchment areas of its primary rivers, which flow in different directions: the Rhine flows north and empties into the North Sea in the Netherlands, the Rhone flows west and reaches the Mediterranean Sea in southern France; the rivers on the southern slope of the Swiss Alps are tributaries of the Po and reach the Adriatic Sea through Italy, and the Inn is a tributary of the Danube and reaches the Black Sea in Romania. Following the melting of ice-age glaciers, the immigration of plants and animals, and hence the Neuropterida, took place upstream along these major rivers. Likewise, these river catchment areas also roughly correspond to the four native languages spoken in Switzerland: German, French, Italian, and Romansh.

During the past 2.4 million years multiple episodes of continental glaciation have shaped and reshaped the Swiss landscape, and have at least twice almost completely covered the country with ice (Hantke 2011). In response, flora and fauna have moved into and out of the country at least 14 times. At the height of the glacial maximum 780,000 years ago, the continental timberline in Europe lay near the French Mediterranean coast, and from there stretched east across central Italy, Croatia, and the Black and Caspian Seas. There were no trees (and hence no tree-living Neuropterida) north of this timberline, an area which includes all of present-day Switzerland. During this time the ancestors of most of the current Swiss Neuropterida fauna probably resided in one or more of three disjunct southern refugial zones: the Iberian Peninsula to the southwest, southern Italy to the south, and the Balkan Peninsula to the southeast; and possibly also in other ice-free regions in northern and eastern Europe (U. Aspöck and H. Aspöck 2005).

The estimated 100,000 year durations of each of the five main periods of continental glaciation, each about ten times longer than their estimated interglacial periods (Ivy-Ochs et al. 2008), were probably sufficient to promote significant genetic drift and/or species segregation in the once continuous Neuropterida populations that repeatedly retreated into these disjunct refugia.

Figure 2. Physical map of Switzerland.

We can speculate about where certain species spent the last glaciations by looking at their present-day distributions, and the distributions of their intraspecific varieties. The genus Chrysoperla provides several examples. The ubiquitous C. carnea, which is not dependent on trees, probably survived north and east of Switzerland in ice-free refugial zones without trees. Today the species is abundant in central and northern Europe and reaches its southern limit on the southern slope of the Alps (Henry et al. 2011). Here, it lives together with C. agilis, which has its northern limit on the southern slopes of the Alps. Chrysoperla agilis probably survived glaciation along the Mediterranean coast, where it is abundant today. The two species are closely related, but are reproductively isolated by species-specific substrate borne vibrational songs (Henry et al. 2003). We can speculate that these taxa resulted from a very recent speciation event caused by one of the longer glaciations. Chrysoperla pallida, a strictly arboreal species, contains populations north and south of the Alps that display slight biological differences, but have identical songs (Henry et al. 2002). Chrysoperla pallida north of the Alps deposits eggs singly, at random, and has whitish cocoons, while populations south of the Alps deposit eggs in groups and have greenish cocoons. The interpretation in this case is that an arboreal species must have re-immigrated from the south after the maximum glaciation (when trees were absent in Central Europe), but during later glaciations the northern populations survived in isolation on trees north of the Alps long enough to develop intraspecific differences from the southern populations, but not long enough to result in speciation.

Many Swiss Neuropterida are considered to be of Asiatic origin (Aspöck et al. 1980, 2001). These species must have immigrated into Switzerland after the most severe glacial maximum ca. 780,000 years ago, but their presence may predate the most recent glaciation, which ended about 10,000 years ago. Although nunataks (ice-free mountain tops surrounded by glacial ice) likely existed in the Swiss Alps during many glacial periods, it seems unlikely that any of the present neuropterid fauna, even high elevation specialists like Helicoconis eglini, survived in the Swiss Alps during major glaciations.

It seems clear that a number of Mediterranean species have immigrated into Switzerland since the last glaciation. About 6000 years ago Switzerland was home to extensive pine forests (Pinus sylvestris L.). Some individuals of Chrysoperla mediterranea, living on pine trees around the Mediterranean Sea, managed to reach these forests and, in isolated populations in Central Europe (e.g. Switzerland, Duelli 1987) and the Caucasus region (Duelli et al. 2015), developed distinct morphological differences, such as a more strongly dilated claw and a darker diapause coloration. These differences allow the separation of “continental” (i.e., northern) C. mediterranea from truly Mediterranean (i.e., southern) populations of C. mediterranea, which probably rarely ranged more than 50 km inland from the coast. But, both morphs have retained identical songs, readily mate, and thus are considered to represent the same species (Henry et al.1999).

Other Mediterranean species have been able to disperse north to the southern slope of the Alps, but have not crossed the Alps to the north. Examples of this include: Italochrysa italica, whose larvae live on the brood of the ant Crematogaster scutellaris, which is limited to the south of Switzerland; and the antlions Gymnocnemia variegata and Neuroleon microstenus, adults of which must have been blown from Italy north into isolated dolomite cliff areas in southern Switzerland (Ticino canton), where they maintain small but perennial populations (Tröger & Rezbanyai-Reser 1998).

Several chrysopid species have recently been detected in the southern cantons of Ticino and Valais. While these may represent Swiss species that were previously overlooked, it seems more likely that they represent recent immigrant species that are extending their ranges northward due to global warming. Apertochrysa zelleri was first detected in Ticino in 1984 (leg. L. Reser), and today it is one of the most abundant Apertochrysa species in ornamental gardens in Ticino. In the same habitat, the Mediterranean species A. clathrata is regularly encountered, after first being observed in Switzerland in 1986 (Duelli, unpubl.). Cunctochrysa baetica, also known primarily from the Mediterranean coast (in Italy, France, and Spain), was first recorded in Valais in 1988 (Duelli 1989), and in 2017 and 2019 has been confirmed in larger numbers (Duelli and Bolt 2020).

Table 2. Neuropterida of Switzerland by canton.
Canton
Order
NEUR
(# sp.)
MEGA
(# sp.)
RAPH
(# sp.)
GLOS
(# sp.)
Totals
Species
(#)
Fauna
(% sp.)
Aargau
56      3      4       -     
63 50.4
Appenzell Ausser-Rhoden
13       -       -       -     
13 10.4
Appenzell Inner-Rhoden
1       -       -       -     
1 0.8
Basel-Landschaft
49      3      3       -     
55 44.0
Basel-Stadt
18      2      1       -     
21 16.8
Bern
33      2      6       -     
41 32.8
Fribourg
12      1      2       -     
15 12.0
Genève
43      2      5       -     
50 40.0
Glarus
31      1      2       -     
34 27.2
Grisons
76      1      7       -     
84 67.2
Jura
20      1      3       -     
24 19.2
Luzern
37       -      3       -     
40 32.0
Neuchâtel
32      2      6       -     
40 32.0
Nidwalden
3       -       -       -     
3 2.4
Obwalden
2       -       -       -     
2 1.6
Schaffhausen
20      2      1       -     
23 18.4
Schwyz
13       -      1       -     
14 11.2
Solothurn
65      2      4       -     
71 56.8
St. Gallen
45      2      2       -     
49 39.2
Thurgau
25      2      4       -     
31 24.8
Ticino
91      1      5       -     
97 77.6
Uri
18       -       -       -     
18 14.4
Valais
89      2      10       -     
101 80.8
Vaud
59      3      6       -     
68 54.4
Zug
9       -       -       -     
9 7.2
Zürich
57      2      5       -     
64 51.2
Switzerland
111       3       11        -      
125  100.0
Columns: GLOS – Glosselytrodea; MEGA – Megaloptera; NEUR – Neuroptera; Order – counts of the Neuropterida species of Switzerland grouped by order and canton; RAPH – Raphidioptera; Totals – counts of the number of Neuropterida species of Switzerland grouped by canton (only), and those counts expressed as a percentage of the total number of Swiss Neuropterida species;

Conservation Issues in Swiss Neuropterida

Intensification of agriculture has led to the decline of several species of Neuropterida in Switzerland. Chrysopa phyllochroma and C. commata have nearly disappeared from Switzerland (Duelli et al. 2016), and the removal of inland dunes in Valais has caused the extinction of Acanthaclisis occitanica (Duelli 2010) from the country. Intense agriculture has also led to the decline of owlfly populations north of the Alps. The central alpine canton of Valais is a stronghold for owlflies and many other neuropterids that require dry habitats. But even here most dry meadows have been converted into irrigated and sprayed vineyards or “improved” grasslands. In the last 75 years, Switzerland has lost 95% of all dry meadows and 85% of natural wetlands (Lachat et al. 2010). All species that live on herbaceous vegetation suffer from agricultural intensification. One of these, Helicoconis hirtinervis, which was originally found in dry Stipetum meadows in Grisons (Eglin 1980), has not been resampled in the last 40 years.

In Swiss forests, fortunately, the situation is much better. Forests covers approximately 33% of the country, with an increase of 21% in the last 120 years (Ginzler et al. 2011), and most forested areas have been legally protected from clear-cutting, fertilizers, pesticides, and overuse for more than 100 years. Because most Swiss Neuropterida are forest or forest edge dwellers (Duelli et al. 2002), the main threat to their populations is pesticide use in adjacent agricultural areas. Similar to forest habitats, running and standing waters in Switzerland are receiving increasing legal protection, so aquatic neuropterid species (3 Sialidae, 2 Sisyridae, and 1 Osmylidae) no longer appear to be threatened at present.

History of the study of Swiss Neuropterida

The first mention of Neuropterida in Switzerland was by Johann Caspar Fuesslin (1775), who recorded seven species: Hemerobius perla Linnaeus, 1758 (now Chrysopa perla), Hemerobius chrysops Linnaeus, 1758 (probably Chrysoperla carnea), Hemerobius phalaenoides Linnaeus, 1758 (now Drepanepteryx phalaenoides), Hemerobius lutarius Linnaeus, 1758 (now Sialis lutaria), Myrmeleon formicarius Linnaeus, 1767, Myrmeleon libelluloides Linnaeus, 1764 (now Libelloides coccajus), and Raphidia ophiopsis Linnaeus, 1758. A more comprehensive list was provided by Meyer-Dür (1875), who noted 44 species, including 2 Sialidae, 7 Raphidiidae, 3 Coniopterygidae, 1 Osmylidae, 14 Hemerobiidae, 12 Chrysopidae, and 5 Myrmeleontidae (including 2 owlflies). Subsequent contributions by Schoch (1887) and MacLachlan (1880, 1884, 1899) raised the total to 55. Steck (1920) reviewed the antlions of Switzerland, but added no new taxa to the fauna. Willy Eglin (later Eglin-Dederding), the most important 20th century specialist author on the Neuropterida fauna of Switzerland, began his 50 years of work on the Swiss neuropterid fauna in 1936 with a publication on species found in the vicinity of Basel (Handschin & Eglin 1936).

Over the years Eglin’s work treated many aspects of the Neuropterida, including taxonomy, distribution, biology and ecology, and his last work on the fauna was published posthumously in 1986. His work significantly increased knowledge of the biology and ecology of Swiss Raphidioptera and Myrmeleontidae (Eglin 1939), and he added, up to that point, 16 species to the list of Schoch (1887). In his publication of the Neuropterida of the central alpine Valais (Eglin 1941) he profited from the intense collecting efforts of N. Cerutti, who died in 1940. By the mid-1940s the Swiss list stood at 82 species. Eglin’s last major work on the Neuropterida was published 1980 and summed up his 40 years of collecting in and around the Swiss National Park in Grisons (Eglin 1980). His final revised list of the Neuropterida of Switzerland (Eglin 1979) reached 104 species and its data were later incorporated into the European Neuropterida monograph of Aspöck et al. (1980). In total, Eglin produced 52 publications on the Neuropterida, including several that were published after his death in 1984.

After 1980, new records of Swiss Neuropterida were incorporated into a WSL database (Duelli and Obrist, unpublished), which was subsequently merged into the Swiss National database of info fauna at Neuchâtel. Aspöck et al. (2001) included some formerly unpublished records for the Swiss fauna, and dropped some species (with good reason) from the fauna. Significant Swiss Neuropterida faunal works that have been published since Eglin (1979) and Aspöck (1980) are: Duelli (1989, 1994, 2010); Duelli and Hartmann (1992), Duelli et al. (2002, 2004, 2006a, 2006b, 2016a, 2016b, 2019); Eglin-Dederding (1980, 1981, 1982, 1984, 1985); Henry et al. (1999, 2002, 2003, 2012); Moretti et al. (2004); Tröger and Rezbanyai-Reser (1998); Wermelinger et al. (2017); and Weissmair et al. (2016).

Over the past several decades faunistic study of the Neuropterida of Switzerland has benefited substantially from material collected by a number of lepidopterists, who have made material available for study from light trap arrays organized primarily to collect moths. By far the most productive contributor in this way was Ladislaus Reser-Rezbanyai, who distributed neuropterid materials to Willy Eglin, Peter Duelli, and Ernst Joachim Tröger, or donated them to local museums. Other entomologists who have collected notable numbers of Neuropterida since 1980 are Georg Artmann-Graf, Heinrich Bachmann, Hermann Blöchlinger, Daniel Bolt, Raymond Delarze, Christophe Dufour, Kurt Grimm, Peter Hättenschwiler, Ulrich Hiermann, Bruno Keist, Andreas Kopp, Lucia Pollini, and Valeria Trivellone.

As part of a national effort to digitize Swiss biodiversity collections, Bärbel Koch, Christian Monnerat, and Peter Duelli have begun a project supported by the Swiss Federal Office for the Environment to reexamine all Swiss-collected Neuropterida specimens held in Swiss museum collections. The goal of this project is to provide modern (re)identifications of these specimens following the many changes that have occurred in the taxonomy and nomenclature of the European neuropterid fauna since 1980. This reassessment will ensure the continued accuracy of identifications on the group of specimens that form the primary foundation of knowledge for the Swiss neuropterid fauna. All reexamined specimens are also being assigned GBIF.CH numbers, to facilitate the inclusion of their occurrence data into global-scale biodiversity assessment efforts.