14 Jul 25

Priorslee Balancing Lake and The Flash

16.0°C > 22.0°C: Sunny intervals with variable medium-level patchy cloud. Moderate south-westerly breeze gusting fresh. Excellent visibility.

Sunrise: 05:04 BST

* = a species photographed today
$ = my first sighting of the species for this year
$$ = my first ever recorded sighting of the species in the area

Back to as normal a Summer schedule visit as I am ever going to achieve this morning. Once around the Balancing Lake; up to and around The Flash; an a return for a second, more gentle, circuit of the lake.

Priorslee Balancing Lake: 05:00 – 06:15 // 07:35 – 10:00

(171st visit of the year)

Bird notes:
- eight Canada Geese when I arrived: another six flew in, some of which departed again.
- only two broods of Mallard noted of four and five birds. I suspect many of the extra adults noted are in fact full grown Mallard duckling, now more or less indistinguishable from the adults.
- a duck Pochard found. Could it be the same one? Where has she been? Hiding?.
- the juvenile Great Crested Grebes were a challenge as the broods with multiple juveniles are now no longer with one of the parents and not easy to find. Also the oldest of the juveniles was not found. I am hoping this is because the lake is so covered in weed that sleeping birds are hard to see.

Bird(s) noted flying over here:
- 2 Stock Doves: together
- 116 Wood Pigeons
- 3 Lesser Black-baked Gulls
- 36 Jackdaws
- 56 Rooks

Counts from the lake area:
- 14 Canada Geese: see notes
- 1 Greylag Goose
- 2 Mute Swans
- 32 (?♂) + 9 (2 broods) Mallard: see notes
- 1 (0♂) Pochard
- 6 + 1 (1 brood) Moorhens
- 95 Coots
- 8 + 6 (3 broods) Great Crested Grebes
- 13 Black-headed Gulls
- 3 Lesser Black-baked Gulls
- 1 Grey Heron

Hirundines etc. noted:
- 1 Swift
- 1 Barn Swallow

Warblers recorded (the figure in brackets is birds noted singing):
- 1 (0) Cetti's Warbler
- 7 (3) Chiffchaffs
- 6 (2) Reed Warbler
- 6 (4) Blackcaps
- 1 (0) Garden Warbler

Noted on the West end street lamp poles around-dawn:

Moths:
*1 Satin Grass-moth Crambus perlella [was Satin Grass-veneer]: flew from vegetation beside a lamp pole with two other, possibly this species
*1 $ Round-winged Muslin Thumatha senex : moth species #70 here in 2025

Flies:
*2 midges

Spiders, harvestmen etc.:
1 Bridge Orb-web Spider Larinioides sclopetarius

Noted later:
Most notable was, to my chagrin, the brief sighting of a mammal that I cannot for the life of think what it could be. The body looked to be the size of a very large and fat Rat with a marked contrast between the grey-brown upper-parts and a very pale buff underside. It did not seem to have a tail of any substance. It popped out of the vegetation and almost immediately saw me and disappeared.

Butterflies:
*Large White Pieris brassicae
Small White Pieris rapae
Green-veined White Pieris napi
Speckled Wood Pararge aegeria
Meadow Brown Maniola jurtina
*Gatekeeper Pyronia tithonus
Peacock Aglais io

Moths
*2 Common Nettle-taps Anthophila fabriciana
3 Straw Grass-moth Agriphila straminella : at least another 10 unidentified grass moths
>15 unidentified grass moths
1 Pale Straw Pearl Udea lutealis
*1 $ Mother of Pearl Patania ruralis [was Pleuroptya ruralis]: moth species #71 here in 2025
6 Cinnabar Tyria jacobaeae caterpillars

Bees, wasps etc.:
Common Carder Bee Bombus pascuorum
Buff-tailed Bumblebee Bombus terrestris
Common Wasp Paravespula vulgaris
*probable Wall Mason Wasp Ancistrocerus parietinus
*small ichneumon

Hoverflies:
Bumblebee Blacklet Cheilosia illustrata
*Marmalade Hoverfly Episyrphus balteatus
Tapered Dronefly Eristalis pertinax
Migrant Field Syrph Eupeodes corollae [Migrant Hoverfly; Migrant Aphideater]
Meadow Field Syrph Eupeodes latifasciatus [Broad-banded Aphideater]
Common Spotted Field Syrph Eupeodes luniger [Lunuled Aphideater]
Tiger Hoverfly Helophilus pendulus
Chequered Hoverfly Melanostoma scalare [Long-winged Duskyface]
*Banded Meliscaeva Meliscaeva cinctella [Banded Thintail]
*Dead-head Hoverfly Myathropa florea [Common Batman Fly]
Common Twist-tail Sphaerophoria scripta [Long Hoverfly; Common Globetail]
Syrphus sp. S. ribesii / S. vitripennis

Dragon-/Damsel-flies:
Common Blue Damselfly Enallagma cyathigerum [Common Bluet]
*Blue-tailed Damselfly Ischnura elegans [Common Bluetail]
Black-tailed Skimmer Orthetrum cancellatum
unidentified hawker in flight

Other flies:
*Tachinid fly Eriothrix rufomaculata [Red-sided Eriothrix]
plenty of unidentified fly species

Bugs:
Common Flower Bug Anthocoris nemorum

Beetles:
7 Spot Ladybird Coccinella 7-punctata
Harlequin Ladybird Harmonia axyridis var. spectabilis
Common Red Soldier Beetle Rhagonycha fulva

Amphibians:
none

Spiders, harvestmen etc.:
money spider Erigone sp.
Zebra Spider Salticus scenicus

New flowers for the year:
*Water Mint Mentha aquatica

Look: after so many clear mornings almost a sunrise. Rain promised tomorrow!

Not a lawn – it would not be so green after all the sun. This is some of the weed growing in the lake and perhaps why so many of the Coots have moved down the other end. The resident Mute Swans are visible in the middle distance.

The head profile identifies this duck as a Pochard. Where has she been?

I looked at many, many "white" butterflies and all were, like this, Large Whites Pieris brassicae until I left the lake and walked back Teece Drive when both Small P. rapae and Green-veined Whites P. napi appeared along the Wesley Brook. The Large White here is a female with two black spots in each forewing.

A Gatekeeper Pyronia tithonus posed well with its wings open a few days ago. Here is the underside view. Two white spots in the black dot. Also a much stronger pattern on the underwing than Meadow Brown Maniola jurtina.

One of three grass moths that scattered from under a street lamp around dawn. This is a Satin Grass-moth Crambus perlella and the others were likely to be the same species.

A new moth for the year on a street lamp pole at dawn: a Round-winged Muslin Thumatha senex : moth species #70 here this year. Some years I record double-figures of this species.

Another new moth for the year: a Mother of Pearl Patania ruralis which, when freshly emerged does indeed look like mother of pearl.

A very worn and faded moth. Luckily its distinctive shape identifies it as a Common Nettle-tap Anthophila fabriciana , a species now more less at the end of its flight period.

Probably a Wall Mason Wasp Ancistrocerus parietinus. This genus contains eight very, very similar-looking species and searching through Steven Falk's Flickr pages (he does not concentrate solely on hoverflies) I cannot match this precisely with any of his photos. His text suggests this is the most likely species.

A tiny ichneumon – look at it against the leaf edging. Perhaps the smallest I have ever noted. No idea as to the species.

As I have remarked before the only species of Cheilosia hoverfly that is not almost all black and which I do not have to double-check with the literature. This is a Bumblebee Blacklet C. illustrata.

"Only" a Marmalade Hoverfly Episyrphus balteatus . I ended up taking dozens of photos of this species today as many of them seemed small and I was hoping for other species. Why were so many small? Apparently hot and dry weather is not the cause. With a size range of 9mm to 12mm it is probably just natural variation.

A smart Banded Meliscaeva hoverfly Meliscaeva cinctella.

Coming to get you: a Dead-head Hoverfly Myathropa florea.

Makes a change from all the Common Blue Damselflies Enallagma cyathigerum. I noted several of these Blue-tailed Damselflies Ischnura elegans.

One of the best and most easily identified flies is this Tachinid fly Eriothrix rufomaculata or as Obsidentify calls it Red-sided Eriothrix. The colour on the right side of the abdomen is somewhat obscured by the wing...

...but shows better here as a different specimen dives in to feed.

A male midge on a street lamp pole at dawn. Initially I assumed the plumed midge Chironomus plumosus but it is not as that species does not have spotting in the wings. So I have no idea.

Not a great photo – sorry. The Water Mint Mentha aquatica has now come in to flower. Squash the leaves and there is no mistaking it is a species of mint.

(Ed Wilson)

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In the Priorslee Avenue tunnel:

Moths: [27 species here before today; no additions]
none

Other Flies:
2 moth flies Psychodidae sp. [Drain Fly or Owl Fly]
16 midges of various species.

Arthropods:
1 White-legged Snake Millipedes Tachypodoiulus niger

Spiders, harvestmen etc.:
2 Missing Sector Orb-web Spiders Zygiella x-notata [Silver-sided Sector Spider]
1 harvestman Opilio canestrinii

(Ed Wilson)

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The Flash: 06:20 – 07:30

(168th visit of the year)

Bird notes:
- many of the geese now have their wings and Canada Geese in particular were flying out in small groups.
- just four Mute Swans.
- yesterday's new brood of six Mallard ducklings was not seen. However a single fast-growing duckling was seen.
- just 12 Tufted Duck.
- two Great Crested Grebes still. One was sitting on a nest site at the top end with the other in close attendance.
- a Grey Heron present throughout again.
- a Nuthatch calling alongside Teece Drive was my first record here for over two months.

Bird(s) noted flying over here:
- c.40 Racing Pigeons flew low north-west c.06:50: a strange time of day?
- 2 Lesser Black-backed Gulls

Noted on / around the water:
- 98 Canada Geese
- 43 Greylag Geese
- 4 Mute Swans
- 15 (?♂) + 1 (1 brood) Mallard: see notes
- 12 (10?♂) Tufted Duck
- 4 + 1 (1 brood) Moorhens
- 83 + 12 (5 broods) Coots
- 2 Great Crested Grebes: see notes
- *8 Black-headed Gulls: all adults
- 1 Grey Heron

Hirundines etc. noted:
- 2 Barn Swallows, briefly
- 2 House Martins

Warblers recorded (the figure in brackets is birds noted singing):
- 5 (3) Chiffchaffs
- 2 (2) Blackcaps

Noted around the area:

Butterflies:
none

Moths [on street lamp poles and in the grass] [55 species here before today; two additions today]
*5 Straw Grass-moth Agriphila straminella [was Straw Grass-veneer]: at least another four "got away" and likely this species
*1 $ Swallow-tailed Moth Ourapteryx sambucaria [species #56]
*1 Straw Dot Rivula sericealis [species #57]

Bees, wasps etc.:
none

Hoverflies:
Marmalade Hoverfly Episyrphus balteatus
Chequered Hoverfly Melanostoma scalare [Long-winged Duskyface]
*$$ Common Pufftail Sphegina clunipes

Dragon-/Damsel-flies:
none

Other flies:
numerous different midges and flies

Bugs:
*Common Flower Bug Anthocoris nemorum
*possible female Orthonotus rufifrons

Beetles:
larvae of Alder Leaf Beetle Agelastica alni
7 Spot Ladybird Coccinella 7-punctata
Common Red Soldier Beetle Rhagonycha fulva

Spiders, harvestmen etc.:
harvestman Dicranopalpus ramosus/caudatus: five all on different street lamp poles

New flowers for the year:
None

Autumn already? No: just the trees shedding leaves in response to their stress from the dry and hot conditions.

Two Black-headed Gulls still in full breeding plumage. I have not seen any juveniles as yet so these are likely failed breeders returning first to their wintering area. The nearest bird seems to have only one leg. Birds often "tuck one up": I am not sure this one has.

My best attempt at photographing a Straw Grass-moth Agriphila straminella. Once flushed, always before I have seem them, they are very wary of a close approach and always hide in the grass where persuading the camera to focus between all the blades is a challenge.

The best moth of the day was this Swallow-tailed Moth Ourapteryx sambucaria. Moth species #59 here this year for me.

A Straw Dot moth Rivula sericealis. It is now late in this species' flight period so this may be the last I see this year.

Two for the price of one. The insect just left of centre is a hoverfly and likely a Common Pufftail Sphegina clunipes . I have not seen any of the five species of hoverfly in this genus previously so I am relying on Obsidentify's confident suggestion. Reading Steven Falk's notes on the internet I would be unable to say which species it is. Below and right of the hoverfly is a Common Flower Bug Anthocoris nemorum .

This strange-shaped insect is not as I first thought a spider but appears to be a female bug Orthonotus rufifrons. In this species the females are brachypterous: that is to say have shortened or much reduced wings; the very different-looking males have a parallel-sided abdomen and are macropterous: i.e. are an insect having long or large wings.

(Ed Wilson)

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2012
Priorslee Lake
Common Tern
Possible Otter
(Ed Wilson)

2011
Priorslee Lake
A female Ruddy Duck
(Ed Wilson)

2006
Priorslee Lake
A drake Ruddy Duck
(Ed Wilson)

2005
Priorslee Lake
Common/Arctic Tern
(Martin Adlam)