Fly: Eriothrix rufomaculata

25 Friday Jul 2025

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bristly black and red fly, British flies, British insects, Eriothrix rufomaculata, fly, insect, parasitic fly larvae

Over the past week I’ve had several sightings of this little fly, Eriothrix rufomaculata, and, though I usually shy away from trying to identify flies, this one is very distinctive. Amongst the checklist of features to look for that are listed on the Naturespot website entry for Eriothrix rufomaculata are the ‘red abdominal side patches’ ♥, ‘silvery face’ ♥, ‘projecting mouth edge’ ♥, and ‘slightly shaded wings’ ♥. It’s also very bristly.

Though the adults are supposedly active from June to October, I presume I’m seeing more of these flies now due to recent hatchings. Look for them feeding on flowers, particularly umbellifers and flowers from the Daisy family, which includes everything from Ragwort to Fleabane, Yarrow to Hemp-agrimony, thistles to Knapweeds, and many more.

Like many creatures, these flies have a dark side to their life cycle: their larvae are parasitic, feeding on the larvae of various moth species, including the little grass moths (the Crambidae) and the very beautiful tiger moth species (the Erebidae).

Fly: Poecilobothrus nobilitatus

26 Monday May 2025

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British flies, fly, long-legged fly, Poecilobothrus nobilitatus

Its name sounds like an incantation a Harry Potter acolyte might chant to turn an annoying peer into a toad, though Google AI suggests: ‘The genus name Poecilobothrus comes from the Greek words “poikilos” (various, or variegated) and “botryx” (a cluster of grapes), likely referring to the diverse and ornate nature of some dance fly species’ and ‘The species name nobilitatus is derived from the Latin word “nobilitatus,” meaning “made noble” or “ennobled,” which could relate to the elegant or showy appearance of the fly, particularly during courtship.’ I can certainly agree that this little long-legged fly is an ornate and elegantly formed creature.

I don’t usually have much luck identifying fly species but, fortunately for me, this one was a male and so it has distinctive white markings on the end of its wings, which it flashes at potential mates during its courtship display. I spotted this specimen sitting on vegetation next to a local footpath but they are usually to be found in wet locations, often sitting on weed floating on the surface of a pond or slow-moving stream.

The unidentified fly

14 Friday Mar 2025

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British flies, fly, unidentified fly

I mentioned in a recent post that one of the ways in which my local biodiversity records office (SEWBReC) supports its volunteer recorders (like me) is through book grants that we recorders can use to buy species guides to help identify our finds. With my grant I have so far obtained one book on spiders and another on craneflies; the third, A Photographic Guide to Flies of Britain & Ireland won’t, unfortunately, be published until October, and I really need it NOW!

It may be that I still won’t be able to identify some species even when I get the book as many flies require examination of genitalia to accurately determine their species but I’m sure it will help me with many of my finds. In the meantime, this handsome little creature that I photographed on my local park railings yesterday will remain nameless, though I will return and edit this post ** at a later date if I do find out which species it is.

** Well, that didn’t take long. It’s the next day and I might have a name for this little fly, Sylvicola fenestralis, thanks to the very kind help of Gary from the UK Safari website. (It really needs more detailed examination to be certain but this identification looks likely.) If you don’t know the UK Safari site, you really should check it out as it contains a huge treasure trove of information on all aspects of UK wildlife.

Nemorilla floralis

17 Tuesday Jan 2023

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British flies, British insects, fly, Nemorilla floralis, parasitic fly, parasitoid

Another day, another summer fly. This one, from last May, is a little bristly beauty called Nemorilla floralis, whose name means something like ‘little visitor to the flowery glade’ (according to a tweet by @ivysuckle). Unfortunately, this fly doesn’t live up to its pretty name as it’s a parasitoid, laying its eggs in the living larvae of various micro moths and butterflies.

230117 Nemorilla floralis

Acletoxenus formosus

03 Thursday Nov 2022

Posted by sconzani in insects

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British flies, colourful fly, fly

And just like that yesterday’s cute little fly has a name, Acletoxenus formosus, thanks to a fellow biodiversity recorder, Graham. Amazingly, my sighting appears to be just the second record of this species in Wales, though I’m sure that’s due to the fact that it’s under-recorded because of its tiny size, rather than because of its rarity. Once I knew its name, I was able to find a short video of its trademark sideways shuffle, thanks to wildlife photographer and enthusiast Phil Booker, who also gives a bit more information about the fly in the description box of his video.

Another mystery fly

02 Wednesday Nov 2022

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British flies, fly

Silly me thinking that this tiny fly was so distinctively marked that it would be easy to identify. It may be part of the Chloropidae family of flies but then again it may not. I think it’s a shame the online resources for fly identification are so limited or require a degree of familiarity with the various fly families that the lay person simply doesn’t have. It certainly doesn’t encourage more people to become interested in flies, yet they can be such visually attractive little creatures.

221102 Chloropidae

253/365 Tachina fera

10 Tuesday Sep 2019

Posted by sconzani in 365DaysWildin2019, insects, nature

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British flies, fly, parasitoid, parasitoid fly, Tachina fera

Flies are fascinating!

This bristle-backed orange-and-black beauty, Tachina fera, is commonly seen in Wales and England any time between May and October. These flies produce two broods over the summer months but their life cycle is perhaps not what you might think. Like almost 300 other fly species in Britain, these are parasitoids – the eggs they lay on plant leaves hatch as larvae that burrow their way inside the bodies of other larvae, the caterpillars of several species of moth, which they then proceed to eat to death. It’s a larvae-eat-larvae world out there, folks.

190910 Tachina fera (1)

It’s a biggie

05 Sunday Aug 2018

Posted by sconzani in insects, nature

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Britain's largest tachnid fly, British flies, diptera, flies, fly, Tachina grossa

At first glance I thought this big brute was a hoverfly, ’cause I know there are some very large hoverflies, but one look at those eyes told me otherwise. Meet Tachina grossa, the largest Tachnid fly in Britain and Europe.

180805 Tachina grossa (4)

As you can see, it feeds on pollen and nectar and, though it’s harmless to us humans, it’s no friend of moths. The female Tachina grossa lays her eggs on living larvae, in particular the large hairy caterpillars of the Oak eggar moth and the Fox moth. The fly larvae eat the caterpillars from the inside, eventually but not immediately killing them.

So, it may look kind of cute in the photograph below but I’m just glad I’m not a large hairy caterpillar.

180805 Tachina grossa (2)

Birth notice

17 Saturday Mar 2018

Posted by sconzani in insects, nature, plants, wildflowers

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Ficaria verna, flies, fly, leaf mines, leaf mining fly, leafminer, Lesser Celandine, Phytomyza ranunculi

I was handing out the cigars last Monday!
Now, you might well think me more than a little mad to be excited about the birth of a fly but this was the first time I had tried rearing one … and it was actually successful, which bodes well for the fact that I’m intending to take part in a fly-rearing investigation this summer (more on that closer to the time).

The fly is Phytomyza ranunculi, a creature whose larvae often make their home in the leaves of Lesser celandine (Ficaria verna). I blogged about this leafminer, its larvae and the pupa here, and it is that pupa which finally hatched earlier this week. I had been told it would take about 3 weeks to hatch but it was, in fact, longer than that – it was 6 February when I found the pupa and 12 March when it hatched, so 34 days in total.

180317 Phytomyza ranunculi (1)

Now, here I must admit to a rookie error. As it was well over the 3 weeks, I had almost given up on its hatching so, on Monday night, when I had a sudden notion to open the container, I didn’t look inside first. The fly popped straight out, perched on the edge for a very brief time – and I managed to get just one photo, and then it flew off. I’ve searched for it in my flat, and it did a quick fly by when I was washing the dishes yesterday, but I haven’t been able to find it, neither to take more photos nor to let it outside.

Leafminer: Phytomyza ranunculi

11 Sunday Feb 2018

Posted by sconzani in insects, nature

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Buttercup, fly, fly larva, fly puparium, leaf mine on buttercup, leaf mine on Lesser celandine, leaf mines, leafminer, Lesser Celandine, Phytomyza ranunculi

You might think there are no insects around in winter but you’d be wrong, as I’ve been discovering in the past week or so. In my checks for blooming wildflowers, I’ve seen the odd Lesser celandine and Buttercup flower and, looking more closely at the plants, I’ve noticed leaf mines on some. And where there are leaf mines, there are insects laying eggs and larvae developing from those eggs to create the mines.

These particular mines are created by Phytomyza ranunculi, an incredibly tiny fly which I haven’t yet seen. But I have seen – and can show you here – a larva and a puparium. I brought home a couple of Lesser celandine leaves, intending to take better photos of them, but I didn’t reckon on them shrivelling up overnight. On the positive side, when I picked up one leaf, a tiny larva was sitting underneath, presumably having popped out of the leaf as it dried up.

A couple of days later I brought home another couple of leaves, for the same purpose, but this time left them in a sealed container. The next day, when I opened it, I saw this tiny speck in the bottom of the container and realised a larva from one of the leaves must have pupated. I’m trying to hatch it so I – and you – get to see the fly. Fingers crossed!