Category Archives: insects

Urophora stylata gall flies

02 Wednesday Jul 2025

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I was having a mooch around an area of rough ground on the edge of some local recreation grounds when I spotted a healthy and robust-looking Spear thistle, so wandered over for a closer look as thistles often provide a home for interesting insects. And I was in luck for there, on top of the first flower I peered at, was this handsome little gall fly, Urophora stylata.

This was my first sighting of this species but, fortunately for me, the Urophora gall flies have quite distinctive patterns on their wings and they each have a preference for a particular species of thistle. Unfortunately for some of you, this gall fly is mostly seen in southern Britain but, according to my internet research (see, for example, this guide from the Montana State Government), it is also present in parts of North America, where it was introduced as a biological control for the Spear thistle, which has been classified as an invasive species in some locations.

After mating, as per my voyeuristic photo above, the female fly lays her eggs, as shown below, after inserting her sturdy ovipositor into the flower heads of the Spear thistle (Cirsium vulgare). The actions of the subsequent larvae cause woody galls to grow within the flower head. The Naturespot website says that these galls are not obvious to the naked eye but ‘can be felt as hard lumps by squeezing dead flower heads’. How to explain that to a passing stranger who politely asks what you’re doing?

Ruby-tailed wasp

01 Tuesday Jul 2025

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This gorgeous creature, clad in glimmering metallic colours of blue and green and red, is one of the Ruby-tailed wasps, the Chrysididae, and that’s as close to a definitive identification as I can come. According to an article I found on the BWARS (Bees, Wasps and Ants Recording Society) website, there are currently 38 species of Chrysid wasps in the British Isles and Channel Islands. Seven of those 38 species are shown on the Naturespot website, and they all look remarkably similar to my eye so I’m not even going to try to put an exact name to the one shown here. And, to be honest, I’m just incredibly pleased that this tiny wasp didn’t immediately fly away as I approached but, instead, allowed me to get reasonably good photos to share with you.

Now, just to be clear, though they look stunning, the Ruby-tailed wasps are almost all parasitic in nature. Some parasitise the eggs and larvae of other invertebrates, including other wasp species and bees; others are kleptoparasites, stealing the food other solitary wasps leave in their nests for their own larvae. Beauty and the beast encased in one tiny but beautiful bundle.

Depressaria daucella larvae

30 Monday Jun 2025

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All parts of Hemlock water-dropwort (Oenanthe crocata) are highly poisonous; from the roots to the leaves, no part of it should be ingested, and the Royal Horticultural Society even recommends wearing gloves to handle the plant. Yet, somewhat surprisingly, when I was wandering around the RSPB Radipole Lakes reserve, where Hemlock water-dropwort is abundant, I found a huge number of these small caterpillars happily munching away on its stems and flowers.

These very attractive creatures are the larvae of the moth Depressaria daucella, common name Water-dropwort brown. They can be seen, on this and a few other species of plants, in the months of June and July, either out in the open when eating or resting within a loosely woven silken spinning.

The UK Moths website rather flatteringly says that the adult moth is a ‘fairly distinctive species with its chestnut-brown ground colour and darker streaking’; all I see is yet another little brown job, rather drab when compared to its caterpillars.

Bug: Deraeocoris flavilinea

28 Saturday Jun 2025

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How bugs are able to colonise places as rapidly as many seem to do always surprises me, and this new-to-me Mirid bug is one of those. Deraeocoris flavilinea was first reported in the UK in 1996.

In the interim 29 years between then and now it has made itself at home across most of the southern and central parts of Britain. Perhaps the fact that this bug’s larvae feed on Field maple and Sycamore, both very common tree species, has helped with its rapid colonisation efforts.

I saw my first, the nymph shown above, on 12 May and, at the end of May, saw my first adult. Since then, I’ve seen several more, even had one walking sedately up my arm, down again and on to my hand, which allowed for a nice close up as my final photo shows.

Bug: Kleidocerys resedae 

27 Friday Jun 2025

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As I think I’ve mentioned previously, I’ve been fortunate to find several new bugs and beetles this year. This is one of those, now seen twice one month apart. Let me introduce you to the Birch catkin bug (Kleidocerys resedae), a member of the Lygaediae, the seed bugs that live in, on and around the seeds of various plants. In this case, as you can tell from the name, Kleidocerys resedae can be found on Birch trees (Betula species), the nymphs in particular munching on the catkins.

These are attractive little bugs, generally red-brown in colour, with some paler markings and transparent wings. There is a darker form Kleidocerys resedae f. privignus, which can be found around Alder trees, and I wonder if the bug shown below might be one of those. I actually spotted it on scrub underneath some trees, one of which was an Alder.

Birch catkin bugs can be found throughout Britain, as well as in North America and Europe, and you might be lucky enough to see them at any time of year, as they overwinter as adults (though they are thought to hibernate in colder climates).

Large whites and parasitism, part 2

24 Tuesday Jun 2025

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A week after my sighting of Large white butterfly larvae that had been parasitised by wasps (see yesterday’s blog post) I returned to the same location to see what might have changed during that time and was surprised to see six pupae, beautiful sculptural objects whose markings varied depending on how long it was since they had pupated. These can’t have been the parasitised larvae I don’t think, so there must have been a large number of larvae munching unnoticed in the grassy area below the signage they were on.

This time, as well as these pupae, a few parasitised larvae and a few caterpillars that looked normal but may still have had wasp larvae in their bodies, there was a new species of parasitic wasp in residence. They looked completely different to the wasp I’d seen the previous week and, rather than the larvae, these tiny wasps were all congregating around the Large white pupae.

As usual, I took a lot of photos and, when I got home, set about researching the possibilities. This time, my guide book offered no assistance but googling produced one probable answer. There exists a wasp that is actually named the White butterfly pupal parasitoid wasp, scientific name Pteromalus puparum, which seems the likely culprit, though this hasn’t yet been confirmed by any experts. I’m intending to revisit the site to see what’s happened while I’ve been away on my little holiday.

Large whites and parasitism, part 1

23 Monday Jun 2025

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Though I’ve been in Wales almost 10 years and was fascinated by British butterflies even before I settled here, I only saw my first Large white caterpillars in June last year. So, when I spotted several more on the large advertising signage fencing off a local building site, I was delighted … until I looked more closely (and just a warning, this is a bit gruesome!).

The larvae were surrounded by small yellow cocoons and, when I looked even closer, I could see small yellowish larvae squirming between the bodies of the caterpillars and the cocoons. It is highly likely that the Large whites have been parasitised by the wasp Cotesia glomerata. In Life Cycles of British & Irish Butterflies, Peter Eeles writes that the wasp

deposits between 15 and 80 eggs inside each young larva that it parasitizes. The wasp larvae feed on the layer of fat beneath the skin of their host, thereby avoiding vital organs, and, when their host is fully grown, break through the skin and pupate within yellow cocoons on or near their host.

If this wasn’t gruesome enough for one morning’s finds, I then noticed a tiny wasp amongst the cocoons. At first, I thought it must be one of the Cotesia glomerata that had hatched, but no. When I checked at home later, a quick internet image search revealed that this did not resemble C. glomerata and, on Wikipedia, I found the information that C. glomerata is itself parasitised by a couple of other wasp species, Lysibia nana [it is listed as L. nanus in British taxonomic listings] and Gelis agilis. I’ve just been reading that the female G. agilis is wingless so I’m wondering if the wasp I saw is L. nanus. As this species is rarely recorded and there are no Welsh records, I’ve sent a query to the parasitic wasp expert at the Natural History Museum; I’ll update this post if/when I get an answer.

**UPDATE** This is the response I received from Dr Gavin Broad from the Natural History Museum: ‘You are correct, your wasps are most probably Lysibia nanus. There is a very similar species, Lysibia tenax, more rarely recorded but with much the same hosts. I don’t believe it is actually a separate species and L. nanus is certainly the usual suspect reared from Cotesia glomerata cocoons.’

The Marbled white and the Skylark

21 Saturday Jun 2025

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Today’s blog title puts me in mind of one of Aesop’s fables. I’m sure there was one where the butterfly was tired and asked the bird if it could ride on its back but the bird ended up eating it? Just kidding! Before I sign off from my blogs about my Weymouth trip I just wanted to share two more random moments …

The Marbled white butterfly (Melanargia galathea), though common in many parts of Britain, is rarely seen in my part of coastal south Wales, so it was a special treat to see three on the wing in Weymouth. The first was a distant blur in a field in the Wildlife Trust reserve Lorton Meadows, an area that looked like it would have good potential for butterflies and wildflowers if it wasn’t for the excessive number of off-lead dogs being allowed to roam everywhere, even into the one dragonfly pond. Fortunately, Portland’s Tout Quarry came up trumps again, and I saw two more Marbled whites there, including this obliging beauty.

Seeing this stunning Skylark up close was another of this trip’s special moments. I was walking back from Portland to Weymouth and had almost reached the information centre at Chesil Beach when I heard Skylark song in front of me. I searched the sky for a couple of minutes before realising that the bird was, in fact, sitting on a bush adjacent to the track directly ahead of me.

Such a singing spot seemed odd but I wondered if there might be a nest in the scrubby area I was walking through and so this male was trying to distract me from going near that. Though I had never intended to move off the path, its tactic certainly focused my attention, and I grabbed a few photos before walking onward.

Lifer: Scarce chaser

19 Thursday Jun 2025

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Here they are, the extremely confiding dragonflies mentioned in yesterday’s blog, the Scarce chasers (Libellula fulva) (also known as the Blue chaser). They were everything you could want in a photographer’s model, perching this way and that to show their best sides; not flying off at the slightest hint of movement behind the camera; the consummate professionals!

So, I managed to get photos of a male, female and the two together in cop. The female (above) is described in my guide book as having an olive-brown thorax and ochre-brown abdomen but, as you can see, she was much more vibrant than those descriptions suggest.

The males have a black thorax and blue abdomen with a dark tip. At a glance, with those colours, they could be mistaken for other dragonflies with similar colouration, until you see their eyes, which are the most amazing shade of blue. (In fact, I’ve just decided to add in a second photo of the male so you can get a better look at those eyes.)

I saw several of these dragons at RSPB Radipole Lakes in Weymouth, which left me wondering why they are called ‘Scarce’ chasers. It seems that, where they are found (in isolated spots in the east and south of England) their populations are relatively small, so they are officially designated as rare. Indeed, in the 2008 British Odonata Red List they were officially listed as ‘near threatened’, so I feel very privileged to have enjoyed such excellent views of these stunning creatures.

Lifer: Norfolk hawker

18 Wednesday Jun 2025

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My wildlife-watching hopes for my short break in Weymouth centred on butterflies and, perhaps, a few birds that I might not see locally, so it was a wonderful surprise to see two new dragonfly species, one extremely confiding (it’ll feature in tomorrow’s blog), one elusive to the point of frustration.

The Norfolk hawker (Aeshna isoceles) was the latter and, on my first visit to the RSPB Radipole reserve, the few times I spotted these dragonflies (easily recognisable by their brown colouring and green eyes), they stayed mostly hidden, perching – when they did actually stop flying – in obscure locations, as you can see from the photos above and below.

Finally, on my last afternoon, when there were fewer people out walking after a morning’s heavy rain and I was battling my way through the extremely overgrown vegetation along the path to the northern bird hide, one of these stunning dragons posed perfectly for me.

Although called Norfolk hawkers, these medium-sized dragonflies have been expanding their range beyond the English county of Norfolk. Their preference for reed beds in swamps and ponds, along streams and ditches, means Radipole provides the perfect location for them to thrive.