Searching for insects

During my stay on Scharhörn I wondered which insects made the jump to this island. It’ s only 15 km to the mainland – but this is a distance that many insects cannot cover without help.

One of the first insects I found on Scharhörn: Eristalinus aeneus (Glänzende Faulschlammschwebfliege). Flies can reach the island without any help.

For sure, many insects were transported by chance from the mainland. But even if they made the jump to Scharhörn, it is not easy to survive: Salt everywhere, only a very small number of plant species grow and storm surges can flood most of the island at any time of the year. A species of sawflies made the jump and reproduced in the European Searocket (Cakile maritima – Europäische Meersenf) were i found some larvae.

Turnip sawfly (Athalia rosae – Rübsen-Blattwespe) feeding on Tripleurospermum maritimum. Scharhörn, September 2019
European Searocket (Cakile maritima -Europäische Meersenf) in the dunes – the presumed food of the sawflies

There are also few species of bugs which occurs on Scharhörn:

Lygus maritimus, Scharhörn, September 2019

Lygus maritimus is adapted to feed in various plants of the salt marshes and I found individuals on Sea Wormwood (Artemisia maritima – Strand-Beifuß) and Tripleurospermum maritimum (Echte Strandkamille). Of course there is a parasite which larvae lives in these bugs – Phania funesta.

Phania funesta – Erdwanzenfliege, Germany (Hamburg), imago, feeding on Tripleurospermum maritimum

There’s always a parasite in nature….. For example, owl moths (Noctuidae) have also made it to the island, as have parasites of them – Ophion obscuratus as well as Netelius sp. which probably live in the caterpillars of moths as well.

Netelius sp. – a species of the Ichneumonidae. Few is known about these insects. Scharhörn, 2019

Surprisingly, I found no spiders and very few beetles. The most interesting of these was Broscus cephalotes (Kopfkäfer) – a nocturnal, predatory ground beetle.

Broscus cephalotes (Kopfkäfer) in front of its burrow. Scharhörn, 2019

In sum, I found just little more than 30 species of insects on the isle. Well, it was very stormy and by far to late in the season for many species. Maybe, there will be a next time to have a closer look earlier in the season.

Searching for insects