Foraging swarms of Spotted darter (Sympetrum depressiusculum)

On three evenings of extremely hot days in July of 2018 and 2019 large groups of high-flying Spotted Darter (Sympetrum depressiusculum) were encountered in the Woldlakebos in the northwest of Overijssel. These swarms were not migrating but stationary. They were foraging on little insects that under these weather conditions were able to fly high.

Mass flight of foraging Sympetrum depressiusculum in Woldlakebos (Weerribben-Wieden) at 8:15 PM on 25 July 2018. Red arrows indicate the flight direction. Photo: René Manger

100 years of Dutch dragonfly research

The availability of opportunistic dragonfly data in the Netherlands spanning >100 years gave us the opportunity to quantitatively assess long term changes in range size. We estimated changes in the number of occupied 5 km × 5 km sites by applying a modified List Length method, which takes into account changes in observation effort. Trends were assessed for nearly all Dutch dragonfly species and the trends were then summarised in MultiSpecies Indicators by taking the geometric mean of the species indices. Overall, dragonflies severely declined in range size between the periods 1850–1950 and 1975–1990. In the period thereafter, strong increases happened, during which many species compensated their earlier losses. The factors driving the changes in dragonflies shifted over time. Until 1975 dragonfly species declined due to deterioration of water systems. After 1975 both climate change and habitat restoration contributed to the recovery of many species. Restoration of dragonfly communities was most successful in running water and least effective in moorland pools.

Arco J. van Strien & Roy H.A. van Grunsven 2023. In the past 100 years dragonflies declined and recovered by habitatrestoration and climate change.

Multi-Species Indicator (±95 % confidence intervals) in 1850–1950 to 2011–2018 for a) all dragonfly species (n = 64)

Odonata wing vein preferences in haemolymph sucking Forcipomyia paludis (Diptera: Ceratopogonidae; Odonata)

In summer 2020, the Odonata fauna in the Weerribben-Wieden National Park was examined at various localities for the Odonata parasite Forcipomyia paludis NatureToday. This park is currently one of the localities in the Netherlands where the species is found every year. Five localities in the area have been studied and many of the Odonata species were found to be parasitized by biting midges. F. paludis have been studied in more detail on photos of the Odonata species and an accurate overview was obtained on which wing veins they parasitize. The highest numbers of biting midges were observed on the Cubitus vein. Furthermore, 91% of all observed midges were on the lower wing veins of the dragonflies and 9% on the upper ones. Biting midges were not observed in all of the sites surveyed in the park (pdf article).

Dragonflies in 2019 in the Netherlands

2019 was a very special year for Anax ephippiger. They were found in various places in 2018, particularly along the coast. Not only in large numbers to the Netherlands, but have also reproduced en masse. Thousands of larval skins have been found.

Leucorrhinia caudalis has settled in the Weerribben-Wieden National Park after a long period of absence and then settled throughout in the Netherlands. After a few observations from 2016, it turned out that Leucorrhinia albifrons is also reproducing in the Netherlands.

2019 was another low point for Aeshna juncea, Coenagrion lunulatum and Coenagrion hastulatum.

Text & Photo’s: René Manger

The return of the Whitefaces in the Netherlands

Leucorrhinia albifrons habitat and just emerged male

Two years ago, Leucorrhinia albifrons was considered extinct in the Netherlands, and the same was true for Leucorrhinia caudalis a little earlier. Both species are now back and we have a total of five species of Whitefaces in the Netherlands.

In 2009 a new species came to the Netherlands: Leucorrhinia caudalis. The species was found in the Netherlands until 1970, but then disappeared. Ten years ago, however, the species was seen in the Wieden-Weerribben National Park.

Many dragonfly lovers were surprised in 2016 because Leucorrhinia caudalis appeared in all sorts of new places, also in urban areas. The species were seen in 2019 across the country, partly at the same locations as in 2018.The arrival of the Leucorrhinia albifrons in 2018 was special. In the Kuinderbos (Flevoland), all five leucorrhinia species were found at one location, a unique situation!

Leucorrhinia albifrons had not long disappeared from the Netherlands, only since 2013. The species has always been very rare. From 2005, there was one small population in Friesland, but it died out eight years later, making it the last population in the Netherlands. However, the species reappeared in 2016, such as in Overijssel, Gelderland, Noord-Holland, Noord-Brabant and Limburg. These vagrants probably came along with the eastern wind from Eastern Europe.

Leucorrhinia albifrons is a species of moderately nutrient-poor fens in a wooded area. They like clear water and there must be a wide zone of plants on the water for the development of the larvae. In 2019, reproduction was established at Staatsbosbeheer in the province of Overijssel. This is a spectacular development that we will follow closely in the coming years, because as far as we know this is the only place in the Netherlands where the species now occurs. Whether the species will be able to maintain itself will we see in the coming years?

Text & Photo’s: René Manger

A lot of fresh Vagrant emperor (Anax ephippiger)

Emerging Vagrant emperor (Anax ephippiger) in the NL

The Vagrant emperor (Anax ephippiger) is a relative newcomer and was first seen in the Netherlands in 1995. In recent years they reproduce more often in southern Europe in summer and since then they have appeared in the Netherlands. Anax ephippiger were seen in almost all of the Netherlands in June 2019. This year is special because there are a lot of them, but also because they arrived early in the summer. The dragonflies are probably from the surroundings of Egypt and it was the first generation from Southern Europe that we never actually see here. Ovipositing have been observed in many places in our country. Anax ephippiger develop very quickly. In their normal range, the dry parts of Africa and southwest Asia, they reproduce in temporary ponds.

From the beginning of August, larval skins and fresh individuals have been seen in the provinces of Noord-Brabant, Gelderland, Utrecht, Zuid-Holland and Limburg. Many dragonfly lovers have started looking for larval skins. It is striking that in the morning only fresh disabled images are found (mostly wings). It has been found that Anax ephippiger are already flying away in the evening. The “good” ones fly away early in the evening or at night. It is still a mystery to which all these images fly, also because they are not seen during the day.

Who knows what to expect next year?

Text and photo’s: René Manger