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Species of the month

Every month it is our aim to highlight a species that is “in-season” and, although not necessarily rare or difficult to identify, has been highlighted by our local recording groups as being somewhat under-recorded and for which new records would therefore be welcomed.

If you or your recording group are aware of species such as this then please contact Bob Foreman.


July: Nudibranchs

Facelina bostoniensis with eggs

Facelina bostoniensis with eggs.
Photo: Olle Akesson

Archidoris pseudoargus

Archidoris pseudoargus
Photo: Olle Akesson

Aeolidia papillosa

Aeolidia papillosa
Photo: Sarah Ward

Limacia clavigera

Limacia clavigera
Photo: Evan Jones

Nudibranchs are commonly known as sea slugs, although they are not closely related to their terrestrial name-sake. They do, however share some physiological traits, leading to them sharing a name: notably they both generally lack the hard shell which is commonly associated with molluscs. The word ‘nudibranch’ literally means ‘naked gill’, being made up of the Latin word, ‘nudus’ (naked) and the Greek word, ‘branchia’ (gill) - referring to their having no protective cover on their gills.

Nudibranchs can be found all over the world, mostly in shallow waters. This means that if you look closely enough you may even find them in a rock pool. Here in Sussex, we occasionally find them on our Shoresearch intertidal surveys, which is always a real treat!

These creatures come in a huge variety of colours and forms. Most commonly on Sussex shores, we spot Sea Lemons, Archidoris pseudoargus, and Grey Sea Slugs, Aeolidia papillosa. However other recent finds include the Orange-clubbed Sea Slug, Limacia clavigera, and Facelina bostoniensis.

Aeolid species such as the Grey Sea Slug have cerata, which are the long projections extending from the mantle. These are used to store stinging cells which the nudibranch obtains through eating cnidarian prey, such as anemones and hydroids. These stinging cells will be discharged into the face of predators if they are threatened - a form of defence which more than makes up for their lack of protective shells!

On the shore, we don’t always see nudibranchs in the flesh, but will find a clue that they are nearby: their eggs. Nudibranch eggs vary in colour and form, from coiled flat ribbons to tiny, delicate little pearls. Nudibranchs are hermaphrodites, possessing both male and female reproductive organs; however they cannot self-fertilise so a pair is required to reproduce. When they mate, double copulation often occurs, meaning that both individuals donate and receive sperm. This reproductive tactic is advantageous as a nudibranch can encounter any mature individual of the same species and they will be a potential mate!

Spring and summer is a great time of year to look for nudibranchs and their eggs; the next time you’re out rock pooling do keep an eye out for these fascinating creatures! And, if you’re lucky enough to find one please send an email to with the details of where and when you found it (ideally with a photo too).

Sarah Ward Sussex Wildlife Trust’s Living Seas Officer



June: Heart Moth (Dicycla oo)

Heart Moth by David Green

Heart Moth (Dicycla oo)
photo: David Green

Heart Moth by David Green

Heart Moth (Dicycla oo)
photo: David Green

Heart Moth habitat by Mark Parsons

Heart Moth habitat
photo: Mark Parsons

Heart Moth records

Total Heart Moth counted by day of month
(all records since 1990 to 2014)

We Heart Moths!

The Heart Moth has only been recorded in Sussex three times this century, but have we been looking for it?

Heart Moth is a UK Red Data Book species (RDB3) and also UK BAP (Section 41 in the Natural Environment and Rural Communities Act 2006). It is one of the 30 top priority moth species for conservation action in South East England based upon Butterfly Conservation’s Regional Action Plan 2016-2025, and it is top 10 priority in Sussex.

The required habitat is described the habitat as “lightly wooded commons and parkland with widely spaced Pedunculate Oaks, usually with other lower vegetation” (Waring and Townsend). Openly spaced trees on woodland rides or edges are also used. The only known UK strongholds are Windsor Great Park and Ashtead Common, near Epsom. However, we seem to have plenty of the required habitat in Sussex, especially in the Weald.

The Heart Moth recorded in Sussex in recent years (all as singles, and all in the north of the county) have all be at garden moth traps (Broadbridge, Sharpthorne and Crawley Down). The moth is known to be rather sedentary, not flying far from its habitat, so these garden sightings suggest there might be hitherto unidentified resident colonies nearby.

The core flight period is late June and early July. The moth is attracted to light and occasionally to sugar, although generally flies very late at night (after 1am).

Please let the SxBRC know if you would like to look for this moth and certainly let us know if you find it.



May: Cardinal Beetles (Pyrochroa spp.)

Red-headed Cardinal

Red-headed Cardinal Beetle (Pyrochroa serraticornis)
Photo: Graeme Lyons

Black-headed Cardinal

Black-headed Cardinal (Pyrochroa coccinea)
Photo: Graeme Lyons

Cardinal larva

Cardinal beetle larva
photo: Graeme Lyons

Cardinal beetle distribution

Distribution of cardinal beetle records in Sussex. The green areas on the map show deciduous woodland coverage, demonstrating that there are large areas of potential habitat where the two species are unrecorded.

There are three species of cardinal beetle in the UK but only two that occur in Sussex. The Red-headed Cardinal Pyrochroa serraticornis and the Black-headed Cardinal Pyrochroa coccinea. Although the two species are similar, the Black-headed is slightly bigger on average, has a black head and is a slightly more vibrant red.

Both species are found in or near woodland, the larvae develop in the layer beneath the loose bark of dead and decaying trees where they are a predator of other smaller saproxylic invertebrates. They are very flat in order to inhabit this space and, with care, can be identified to species relitively easily.

Along with many soldier and long horn beetles they are only on the wing for a short period of time in May and June but unlike them they are rarely encountered on flowers. Since 2014, neither species is considered to be scarce and you are equally as likely to encounter either species in suitable habitat.

Despite the two species bieng common and easy to identify there are surprisingly few records in the SxBRC database. We have 407 records of P. srraticornis and only 304 of P. coccinea. If you see either of these beetles in the next few weeks please enter you sighting, ideally with a photo, into iRecord.



April: Bee-flies (Bombylius spp.)

Chloe Wrench and Bombylius major

Chloe Wrench watches a Dark-edged Bee-fly
Photo: Dan Wrench

Dotted Bee-fly

Someone you might recognise gets down with a Dotted Bee-fly

Bee-fly distribution in Sussex

Map showing distribution of Bee-fly records in Sussex.

Bee-fly records

Since Bee-fly Watch started in 2016 we have been sent lots of records - thanks to all who have contributed. Will we find even more in 2018?

National Bee-fly Maps 2017 and 18

Evidence of a late spring in 2018?

Spring time heralds in one of Britain’s cutest insects, the Dark-edged Bee-fly (Bombylius major). They are often mistaken for bumblebees, in what is suspected to be a case of Batesian mimicry (where a harmless organism has evolved to look like a potentially harmful organism, in this case the stinging bumblebee). Unlike bumblebees however, they have no sting, a single pair of wings (unlike the bees, which have two pairs) and don’t live in colonies. They do, however, spend much of their time buzzing around acting as jolly good pollinators, using their long proboscis to collect nectar from flowers. This proboscis has been known to alarm some who are unfamiliar with the species, causing concern that the fly is a type of mosquito or other biting fly capable of inflicting harm. There is no reason to worry though, the long mouthparts are used only for feeding and act much like the mouth of a butterfly, allowing them to reach into the deep nectar stores of flowers. The larvae of the bee flies are nest parasites of various solitary bee species. The adult female will collect small amounts of sand on the tip of her abdomen, which will be used to coat her soft, light eggs. She will then find a nest hole and ‘flick’ the sand-weighted egg into the nest, where the larva will hatch and feed upon the larvae of pupae of the solitary bee.

The Dark-edged Bee-fly is the most common of the two Bombylius bee flies in Sussex, with the other species, the Dotted Bee-fly (Bombylius discolor) being less common and with more limited distribution. Dark-edged Bee-flies normally start to become active around March each year, with the first recorded sighting coming in on March 15th this year (later than the March 2nd record from last year!) They can often be seen in gardens or parks and are especially common in areas with ground-nesting solitary bee populations. Both are great species to go out looking for, especially the slightly rarer dotted Bee-fly!

Since 2016 the recording scheme has run an annual Bee-fly Watch, encouraging people to look out for any of the spring bee-flies and send their records in. The project has been very successful in increasing the number of records - before 2016 the scheme received about 200 bee-fly records per year, but with a small amount of promotion via Facebook and Twitter we had over 800 records in 2016 and nearly 1,300 in 2017.

This year records have been thin on the ground so far, with the cold weather in March, but bee-flies will be out and about as soon as it warms up a little. If you see one please do add the record to iRecord - last year there were quite a lot of records that were new for their 10km-square, and some signs of range expansion in Scotland, so there are still new discoveries to be made.

For information on how to take part, and to download an identification guide, go to Bee-fly Watch on the recording scheme website. The scheme is also on Twitter and Facebook .

Alex Dye and Martin Harvey, Soldierflies and Allies Recording Scheme

There are only four members of the genus Bombylius native to the British Isles and of the two that are recorded in Sussex; the Dark-edged Bee-fly (B. major) is the commoner and more widely distributed of the two whereas B. discolor is be more coastally distributed and restricted to the far east of the county and the eastern Downs. One thing is certain we don’t have many Sussex records of either species, only 205 for B. discolor and 910 for B. major.

Not only does the Soldierflies and Allies Recording Scheme , the organisers of Bee-fly Watch want your records, the SxBRC would also be very keen to have them too. In order for both the SxBRC and Soldierflies and Allies Recording Scheme to get them, please submit any sightings of Bee-flies (ideally with a photo) via the iRecord website or mobile app.

More information:
More about bee-flies
Identifying bee-flies in genus Bombylius



March: Sarcoscypha austriaca

Scarlet Elfcap

Scarlet Elfcap, Monkmead Wood, West Sussex (26 February 2017) Photo: Mark Colvin

Sarcoscypha austriaca

Photo-microscopy images of Sarcoscypha austriaca ascospores

Habitat and distribution
Sarcoscypha austriaca or Scarlet Elfcup is a widespread species that likes damp woodland with Salix and Alnus and is often found on moss-covered logs of these species near standing water. Unlike many of the other larger more colourful fungi, this species starts to appear at the beginning of the year and tends to reach full maturity in late February to March.

Similar species
There are several very similar species in the genus which can only be separated with microscopy:

Without microscopy, Sarcoscypha collections should be submitted as Sarcoscypha sp. or Sarcoscypha cf. austriaca. Fresh collections for species determination are welcomed and can be sent to:

N. Aplin
21 Shetland Close
Pound Hill
West Sussex
RH10 7YZ



February: Brown Hairstreak

Brown Hairstreak egg

Brown Hairstreak egg photographed at Woods Mill in January 2018

Now is the perfect time to search Blackthorn hedges for Brown Hairstreak eggs. We have more records of the eggs of this rare and elusive species in our database than we have for adults. They’re quite easy to spot once you get your eye-in, brilliant white and pin-point size, they look like microscopic sea urchins when seen through a hand lens.

The female butterfly lays her eggs singly in the axil of the thorn and stem on scrubby Blackthorn bushes. They will usually be found no more than 1.5 m above the ground. It would seem that the butterflies are only interested in plants growing on Wealden Clay soils and to a lesser extent the Upper Greensand and Chalk formations. This geological preference limits the eastern extent of its distribution, Plumpton station being its most easterly outpost in Sussex.