Introduction

I’ve mentioned a few times in the other posts of the blog that one of my goals is to provide an opportunity for others to learn, with me, about that natural world around them. Because it is through a blog there will be some repetition, but that repetition will hopefully help the reader become aware of some of the details that make a difference when trying to identify or categorise what we see around us.

The Nature 101 series provides some of those building blocks that support our knowledge growth. These species highlights can be taken as a type of case study where we can not only apply that knowledge but also become aware of our limitations through questions that come up that we cannot immediately answer. This we can use as sustenance for our quest to gain more knowledge (a never-ending cycle if we’ve found something that interests us). So, without further ado … today a fly …

Milesia crabroniformis

When we look at the images above, we notice that the fly looks a bit like a bee or wasp. They are active at the height of summer, especially in August and when you see them flying around you might have some concern if you’re not sure what you’re looking at because they are big, as they can be up to 25 mm in body length, as big as a European hornet (Vespa crabro), and one of the largest flies in Europe.

Here is where Nature 101 Naming comes in … crabroniformis (Latin) means “shaped like crabro”, the European hornet. Here’s another reason why I started learning the scientific names, so I could start seeing links between species “behind the scenes,“ as it were. This hoverfly (more on that later) mimics a hornet. So, there are two paths forward that we might be able to find an answer to with our current knowledge:

• How can we tell it is not a wasp or bee?
• What exactly is mimicry?

The latter I’ll leave for a Nature 101 post … I mean I have to create content for the blog. But it might first calm the mind a bit if we can figure out which details show us that this hornet-looking fly is actually a fly and not a hornet.

Milesia crabroniformis is part of the hoverfly family. The order name for flies is Diptera … from our Nature 101 Lepidoptera post we know that “ptera” means wing … “di”, well that means two … flies have two wings, compared to bees and wasps (Hymenoptera) who have 4. One of the tricky things is that Hymenoptera have little hooks that connect the two wings on each side making it look like they only have two wings in total, but if you look closely on a photo, you’ll actually be able to make out 4.

A second clue, and one that should jump out straight away … is the size and shape of the antennae. They are like two nibs that stick out from the middle of the face, whereas Hymenoptera have long, segmented antenna.

The third clue, but one that can be more difficult to determine, is the eyes. This does bring me to another interesting observation. If we go back up to the images above and look at the two Milesia crabroniformis there, have a look at the eyes … they are different. One has them touching ever so slightly in the middle, where the other has them clearly separated along the whole central section. What is going on here? In many hoverflies, males have eyes that touch whereas female’s eyes do not touch. We can therefore not only ID the species but also the sex.

Just before I round off the post, a few more details about this fly. It is mainly found in Europe from about mid-France southwards, as well as in Northern Africa. It is not very common, one of the reasons being that it needs mature woodland, oak trees, and beech trees, where it lays its eggs in rotting wood. You often find them feeding on the nectar of umbellifers (as seen in both photos), which have big “flower heads” made up of many tiny little flowers, so they do not need to have a long tongue to get down into the flower (like a bee or butterfly) but can hoover it up with their mouthparts.

Conclusion

I hope I’ve been able to show how just a little bit of knowledge and information can point us in a direction that can help us identify or understand and insect or animal better. We don’t have to know everything about it straight away, we can look up more in-depth information at a later date. However, we can start seeing connections to it and things we already know.

It is easier to bring this information across in the field … this is one of the basics of adult learning, where we learn best by doing and use all our sense to process information … but as I’ve said before, I am still trying to find a good way to package this information so that a large chuck will stick till the next blog post, and then we can go from there.

See you in the next one (hopefully on Odonata).