Story | 30 Aug, 2021

Meet the Hoverflies Experts: Jeroen van Steenis

In this edition of “Meet the Expert” we hear from Dutch entomologist Jeroen van Steenis. With his fellow assessors, Jeroen has been playing an essential role in the assessment of Europe's hoverflies, building and gathering the necessary knowledge to successfully conserve these species across the continent. You can find the interview here. 

This is the sixth in a series of interviews with the network of Experts involved in developing the IUCN’s European Red List (ERL) of Hoverflies. The project aims to assess the extinction risk of hoverfly species across Europe, and will contribute to guiding decisions and conservation action for these species at the European level.

In this instalment, we introduce you to Jeroen van Steenis, a Dutch entomologist and researcher from the Naturalis Biodiversity Center in Leiden, Netherlands. Jeroen’s fascination with insects started when he was a young member of the “NJN”, the Dutch Youth Association for Nature Studies. He was thirteen years old when, during summer camp, he caught his first Eristalis tenax – the common drone fly. Once he got home, young Jeroen built his own collecting net from scratch and started cataloguing insect species, gathering notes and drawing their characteristics. Jeroen’s investigative nature never left him, as proved by his favourite hoverfly species: the extremely rare Sphiximorpha petronillae, a wasp mimicking insect which has been recently collected for the first time by Jeroen himself.

Sphiximorpha petronillae female on Quercus pubescens, Kamenički Park, Novi Sad, Serbia. Photo J. van Steenis

Sphiximorpha petronillae female on Quercus pubescens, Kamenički Park, Novi Sad, Serbia. Photo J. van Steenis

Photo: J. van Steenis

From a young age, Jeroen has been particularly passionate about the study of hoverflies (Syrphidae). When asked about where this curiosity came from, he recalls the “excitement of catching these little insects by hand” and how the variety and peculiar behaviour of such species intrigued him as a young entomologist. Eventually, this interest led him to start writing about insects, focusing since his early twenties on species recognition and taxonomical studies, and accumulating invaluable knowledge for the creation of the European Red List of Hoverflies.   

Jeroen believes in the importance of studying and conserving hoverflies. “Many of them are very important plant pollinators” he says, but this is not the only role they play in ecosystems. Throughout their lifecycle, hoverflies serve as food for birds and other insects, they feed on a variety of insect larvae, and they are decomposers of various waste products. On top of that, the entomologist points out how “hoverflies can be helpful allies against pests and for the health of farmlands and ecosystems”.

When confronted about the many challenges that pollinators – hoverflies included – face, Jeroen finds hope in the “increased knowledge on the usefulness of the species for agriculture and in the increasing awareness of their benefits for nature [which] has led to several projects to influence public opinion and policymakers throughout Europe”. Jeroen’s main concern for these species lies with the intensification of agriculture, which is heavily using pesticides. He explains that such chemicals pose a deadly threat to hoverflies, killing different types of organisms indiscriminately and ultimately leading to a situation in which agricultural landscapes will lose most hoverflies and pollinators species, with decreases in population and richness even affecting protected areas.

Jeroen believes that gathering information on European hoverflies, their habitats, distribution, and conservation status is the first step to effectively protect these species. He suggests that the creation of an ERL of Hoverflies represents a massive opportunity to build knowledge on such important insects. Furthermore, he thinks that the Red List might be an opportunity to “show the European citizens and especially its politicians the importance of this group and its threats”, by raising awareness and creating interest in the public but also “by attracting financing and eventually multiplying conservation efforts across the continent”.

Jeroen van Steenis during fieldwork in Denmark, July 2019. Jeroen van Steenis during fieldwork in Denmark, July 2019. Photo: Photo provided by Jeroen van Steenis