I keep wondering why so many insects that are native both in the Netherlands/Flanders, and in Great Britain, do have a Dutch name, but no English one. This hoverfly is a very common species in the UK (according to Wikipedia), but is just 'some kind of hoverfly'... while we call him 'lemon dangling hoverfly' (there is also the 'common dangling hoverfly, that is very similar).

Years ago, I found a Dog Vomit's Slime Mould in my garden. For years I didn't see a slime mould (didn't look for them really), but yesterday there were several of them in the hay-meadow in our garden. Not the colorfull one of last time, but a species that doesn't seem to have an English name. (The Dutch name could be translated as 'greater chalk-foam').
It starts as a pale yellow slime mold, that gradually fades to cream white, and end as a blackened mass.