Hoverflies, Hoverflies, and a few Moths – Jul26

Outings with the Yorkshire Naturalists’ Union, leading a fieldcraft session with Barnsley Nats & moth trapping in my garden - come see what I found.

We are now past the longest day of the year and the days are getting shorter and the nights longer. Yet, as I sit down to write this article, we seem to be in the grip of another heatwave—the second, or perhaps the third of the summer. I’ve honestly lost count.

Many of you have been out spotting hoverflies and sharing your sightings, which is wonderful to see. I hope my article, notes and ‘Hoverflies on the Wing’ collations are helping you discover more of these fabulous flies. I know I’ve certainly been seeing a wider variety of species this year, although I can’t help wondering how the recent spells of hot weather have been affecting them.

Hoverflies are often known as “sun flies” because they become active when the sun shines. However, they are surprisingly sensitive to temperature and, like Goldilocks, prefer conditions that are ‘just right’. When temperatures fall below around 8°C, many species enter a state of torpor and become inactive. At the other extreme, when temperatures climb above 25°C, hoverflies often retreat into shade or sheltered spots to avoid overheating.

In many ways, I’ve behaved much like the hoverflies during this latest heatwave, seeking refuge from the hottest part of the day whenever possible. Despite the high temperatures, I’ve still managed to get out with the Yorkshire Naturalists’ Union, lead a session for the Barnsley Naturalist Association, and even fit in a little moth trapping in my garden.

Denby Delf with the Yorkshire Naturalists’ Union.

This gem of a nature reserve lies near the village of Upper Denby, close to Huddersfield. It is a rich patchwork of habitats set within a wider pastoral landscape of pasture and arable farmland. The name delf is derived from the Old English word meaning “to dig” and refers to a place that has been excavated. Appropriately, Denby Delf was once a working quarry, supplying stone for the construction of the spectacular Denby Dale Railway Viaduct.

Today, the site is owned and managed by the Garganey Trust. Covering around 30 acres, it supports a remarkable variety of habitats, including wildflower meadows, bilberry heathland, acid grassland, scrub, woodland and, of course, the former quarry itself. The reserve also boasts spectacular views across Emley Moor and the Dearne Valley, making it as rewarding for the scenery as it is for the wildlife.

This was a new site for me and whenever I visit somewhere for the first time, my instinct is simply to explore. I suppose it’s the child within me that wants to wander down every path and investigate every nook and cranny. Of course, if I come across a patch buzzing with hoverflies, I’m more than happy to stop and linger for a while. That’s not always easy when you’re part of a group, however, so as the day went on our larger gathering gradually splintered into smaller groups as people followed their own interests and discoveries.

Although it was a stonking hot day, the temperature here felt much cooler and more pleasant. As there were plenty of eyes in the field recording different groups, I decided not to record every species I encountered and instead focused on one of my specialist interests: insects. By the end of the day, I had logged 52 records, including 17 species of hoverfly (listed below), nine butterfly species—including Small Heath—and 11 moth species, among them Phoenix, Map-winged Swift and July Highflyer. The moth records were courtesy of Doug’s moth trap, which had been set out the previous evening and opened during our lunch break.

Many of the hoverflies recorded were species commonly found in gardens or just beyond the garden gate. Two species, however, stood out as ones I don’t believe I’ve mentioned before: the Furry Dronefly (Eristalis intricarius) and the Bumblebee Blacklet (Cheilosia illustrata).

Furry Dronefly (Eristalis intricarius)

The Furry Dronefly is one of those hoverflies that can easily be mistaken for a bumblebee. A sexually dimorphic species, with females generally being larger than males and with different markings. Females have a pale, often whitish tail see below, giving them the appearance of a Buff-tailed or White-tailed Bumblebee, while males sport a reddish-orange tail. Unlike bumblebees, however, the Furry Dronefly has distinctive dark wing spots and black-and-pale-yellow striped legs, features that help distinguish it from a bumblebee which don’t.

Bumblebee Blacklet (Cheilosia illustrata)

I always enjoy finding this hoverfly as it reminds me of one of those delightfully scruffy Charlie Bears, which are so cute. Although it has a bumblebee-like appearance, it isn’t a particularly convincing mimic. Nevertheless, it is a distinctive member of the Cheilosia genus (the others being little black jobs) and is usually recognisable by the long white hairs across the top of the abdomen, a tuft of reddish hairs at the tip, its black face and the dark markings on its wings.

In total Hoverflies spotted: (17)

All records were submitted to the Yorkshire Naturalists’ Union for inclusion in their records database, and I look forward to reading the full report when it is published. It is certainly a site that deserves a return visit, as I am convinced there is much more still waiting to be discovered.

RSPB Old Moor – leading a walk about Hoverflies & Dragonflies for the Barnsley Naturalists

I last reported on visiting Old Moor in February with the British Naturalists’ Association (BNA). This time, it was the turn of the Barnsley Naturalists.For me, the reserve undergoes a seasonal transformation. In winter it is renowned as a birdwatching destination, but by summer it becomes a spectacular haven for insects.

In fact, our first notable sighting came before we had even left the car park. A Six-belted Clearwing (Bembecia ichneumoniformis) was resting on a flower, providing an excellent opportunity to show it to those who had arrived early. This fascinating day-flying moth has transparent wings and six distinctive yellow bands around its abdomen, along with orange scales on the tips and central bar of the forewings. A species more commonly associated with calcareous grasslands and coastal habitats, it seemed something of an oddity here.

Old Moor is also becoming an increasingly important site for dragonflies. Recent additions to the reserve’s dragonfly list include Norfolk Hawker (Aeshna isosceles), Red-veined Darter (Sympetrum fonscolombii) and Lesser Emperor (Anax parthenope), all exciting species to see establishing themselves in South Yorkshire. Unfortunately, none of which were flying around on the day.

My beloved led the dragonfly section of the walk. With such a large turnout, we divided into two groups. One group headed to the ponds and pools in search of dragonflies and damselflies, while the other remained closer to areas of shade. After an hour, the groups swapped over.

The split served a practical purpose. It was a particularly hot day and spending two hours standing in full sun around the water’s edge would have been uncomfortable and potentially unsafe. By rotating between habitats, everyone was able to enjoy the wildlife while staying relatively cool.

Here is a listing of sightings:

Dragonflies

Emperor (Anax imperator), Black-tailed Skimmer (Orthetrum cancellatum), Four-spotted Chaser (Libellula quadrimaculata), Broad-bodied Chaser (Libellula depressa), Brown Hawker (Aeshna grandis), Ruddy Darter (Sympetrum sanguineum) and Common Darter (Sympetrum striolatum).

Damselflies

Banded Demoiselle (Calopteryx splendens), Red-eyed Damselfly (Erythromma najas), Blue-tailed Damselfly (Ischnura elegans), Common Blue Damselfly (Enallagma cyathigerum) and Azure Damselfly (Coenagrion puella).

It was at Old Moor that I was first introduced to hoverflies many years ago by the current chairman of the BNA. The species in question was the Marsh Tiger (Helophilus hybridus), a close relative of the Footballer (Helophilus pendulus). The two species can be distinguished by the markings on the abdomen and, in males, by the absence of a break in the yellow bands between tergites 2 and 3 in H. hybridus (see below).

It was therefore a real pleasure to encounter the Marsh Tiger again during my recce visit, in a pool not far from the spot where that first specimen had been shown to me all those years ago. Some sightings are special because of the species involved; others because of the memories they bring back. This one was very much the latter.

Pic: Left – Footballer (Helophilus pendulus); Right – Marsh Tiger (Helophilus hybridus). Adapted from references 1 & 2.

My session focused primarily on fieldcraft and techniques that can prove useful when studying hoverflies—or indeed any other insects.

After my fieldcraft talk, we headed out of the shade into sunny areas. Some members tried the experience of allowing hoverflies to land on their hands, while for others I was able to use a bat detector to listen to the distinctive hum of the male Humming Flowerfly (Syrphus ribesii), as they rested on leaves close to their lekking spot.

Several participants gravitated towards the umbellifers, using binoculars to study hoverflies from a distance without disturbing them, having explained to them they can easily be disturbed by sudden changes in shading, if you approach a flower too quickly. Others made use of the specimen pots I had brought along, temporarily capturing insects to examine them more closely with a hand lens before releasing them. A sweep net proved popular, particularly in the longer grass, where a variety of butterflies, beetles and other insects were found. Meanwhile, some members explored identification tools such as iNaturalist or made use of field study sheets they had brought with them.

It was wonderful to see everyone getting stuck in—observing, identifying and learning through direct experience. There is something immensely satisfying about watching people gain confidence and discover things for themselves.

Unfortunately, I forgot to take any photographs during the session, so you’ll just have to trust me that I wasn’t standing there talking to myself!

Given the heat, we held the fieldcraft talk in the welcome shade of the outdoor classroom, which was particularly appreciated by the group returning from their first circuit of the ponds and pools looking rather warm.

Hoverflies spotted over the 2 sessions see table below. (15)

Disclaimer: Small Spotty-eyed was not seen at the event only the recce, which was a bit of shame.

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Moth Trapping at Home

I ran two moth-trapping sessions a week apart, one on 8 July and the other on 16 July, both in my garden using a Heath trap. While there was some overlap between the species lists, I was pleased to find a good number of differences between the two nights.

During the first trapping session, I recorded 22 species.

The highlights included the Canary-shouldered Thorn (Ennomos alniaria), whose striking yellow thorax makes it easy to see how it earned its name. Another standout species was the Swallow-tailed Moth (Ourapteryx sambucaria), a distinctive pale-yellow moth reminiscent of the Swallowtail butterfly in outline. Although less flamboyant than its butterfly counterpart, its elegant shape and long pointed tails, marked with dark brown spots at their bases, make it a beautiful insect in its own right.

There was also a Green Silver-lines (Pseudoips prasinana), although it was rather faded, along with plenty of Riband Waves displaying a range of brown colour variations. Other notable catches included Dun-bar and several Yellow Underwings, both Large and Lesser.

I have a particular fondness for micro-moths, so I was delighted to trap my first Netted Tortrix (Acleris forsskaleana). The intricate network patterning on the wings makes it easy to see where it gets part of its common name. The larvae feed within spun leaves or flowers of Sycamore, yet I have never seen any on the tree so it was a delight to get the moth, nevertheless.

The second trapping session produced 20 species.

Of the macro-moths, the highlights were Dusky Thorn (Ennomos fuscantari), Marbled Beauty (Cryphia domestica) and Dark Arches (Apamea monoglypha), all welcome additions to the night’s catch.

Once again, however, it was the micros that stole the show. Meal Moth (Pyralis farinalis), Rosy Tabby (Endotricha flammealis) and one of the Oegoconia species were all trapped. Unfortunately, identifying Oegoconia to species level is notoriously difficult and often requires examination of the genitalia, something I was not prepared to undertake.* The larvae of all three species are strongly associated with leaf litter and dried plant material, both of which are abundant in my wildlife-friendly garden.

*(No moths were harmed and all were released back into the wild).

For those following my annual species count, these records bring my total for the year to 788 species—an increase of 79 species since my previous report in June (click here if you missed any of my previous reports). Of those 79 additions, 15 were lifers, meaning they were species that I had never recorded before.

Whatever the remainder of the summer brings, it is encouraging to know that there are still plenty of new discoveries waiting just beyond the garden door.

What ‘lifers’ have you spotted in the last month?

References:

1. Claude j, Siffointe R, Speight M.C.D (2025) The Syrphidae in the Siffointe collection at the Musee des Confluences in Lyon (France) (Diptera). Rev.Fr Entomol. Gen 7 (2)

2. Ball.S and Morris R 2024 Hoverflies of Britain and Ireland 3rd Edition WILDguides. Princeton University Press.

3. Waring P,Townsend M, (2017) Field guide to the Moths of Great Britain and Ireland 3rd Edition. Bloomsbury.

4. Sterling P, Parsons M (2012) Filed Guides to Micro Moths of Great Britain and Ireland. British Wildlife Publishing.

Links

https://garganeytrust.org.uk/reserves/denby-delf/

https://en.wikipedia.org/wiki/Denby_Dale_Viaduct

https://www.ynu.org.uk/

https://www.rspb.org.uk/days-out/reserves/dearne-valley-old-moor