Brighton blues

With our changing climate, distributions and abundances of a wide range of invertebrates are ever-changing. In this regard, the headline butterfly event of the year was the record-breaking influx of long-tailed blues, reaching the British coast from their regular haunts of southern Europe. At the moment, in September, the offspring of the first wave of primary migrants are emerging from the broad-leaved everlasting-pea plants on which the females had laid their eggs in late August, allowing keen lepidopterists another chance to see this elusive species. However, I did not need this second chance – I was fortunate enough to lay eyes on some of this year’s earliest arrivals.

Walking up Whitehawk Hill on the late summer day of 29th August felt typical, 20 degrees yet with a fresh breeze blowing up from the Channel. However, what I was about to witness was an indication of our warming planet.

Upon reaching the top of the hill, I immediately saw two small butterflies spiralling frantically upwards against the expanse of Brighton in the background. I knew exactly what they were – territorial male long-tailed blues. These were small, dainty yet tireless butterflies, which had crossed the Channel and much of Western Europe to gambol between the community allotments and the scrubby border of the local nature reserve in the shade of the transmission tower.

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During brief interludes between the combat, these two males and a further individual occasionally paused on ground vegetation, allowing photo opportunities and examination of the species’ beautiful intricacies. The long-tailed blue is so-called on account of the two ‘tails’ which project backwards from the hindwing. These mimic the antennae of the butterfly, and coupled with the eye-spots on both the upper and lower surfaces, the tactic is to make predators attack this end of the insect, thinking it is the head. This protects the actual head from any damage from hungry insectivores.

The photo below shows one of the more worn-looking blues. There are chunks missing from the left hindwing where the eye-spot usually is, suggesting a predator mistakenly attacked the rear end of the butterfly, fooled by the fake antennae. This left only superficial damage to the butterfly.

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I did not expect finding these long-tailed blues to be quite so easy, and in the past it certainly wouldn’t have been. The first British record of this species was from Brighton all the way back in 1859 (leading to one of its earlier vernacular names being the Brighton argus), although in the succeeding 80 years it had only been sighted again 36 times. The number of sightings more than doubled between 1940 and 1988, with a large proportion of these being during an influx in 1945. However, it took until 2013 and 2015 before the long-tailed blue numbers really became significant, when relatively major immigrations took place into the southern counties. Already it is looking likely that the 2019 influx will surpass all previous influxes.

But why are these long-tailed blues making an effort to reach our shores? There are many other butterfly species which have similar distributions to the long-tailed blue in southern Europe, although they have made no attempt to colonise the UK. However, the long-tailed blue is not only found around the Mediterranean – one of the world’s most successful butterfly species, its distribution also stretches right down to Australia. For such a small lepidopteran, its flight is powerful and determined, showing no reluctance to cross seas and mountain ranges such as the Channel and the Pyrenees. Furthermore, the long-tailed blue is renowned for its ability to pass through its entire life-cycle incredibly quickly. Despite most primary migrants only appearing in the UK in late August, their offspring already started to emerge as adults in mid-September. This allows the long-tailed blue to gain a foothold on new lands with great speed, which gives this species a huge advantage in the face of increasing temperatures in the long-tailed blue’s ancestral homelands. Although the current year-round climate of the UK is too cold for the species to overwinter, it is quite possible that it won’t be long before it is resident in the UK and there will be more chances to admire this resolute butterfly.

 

The Saxons are invading again

In July 1987, Dolichovespula saxonica, commonly known as the Saxon wasp, was first recorded in the UK at Juniper Hall in Surrey. In the 32 years that has since passed, the species has spread throughout south-eastern England, with scattered records further north to Yorkshire and a handful of sightings from Scotland. Eventually, at the end of July this year, I saw my first ever Saxon wasp, in the same county it was first seen. It is one of two social wasp species which have colonised the UK in modern times, along with Dolichovespula media, the median wasp, which was first found by Steven Falk in 1980 in Sussex.

Contrary to what many people might expect, there are several thousand wasp species in the UK, ranging from tiny parasitic wasps which barely reach 0.2mm in length to the docile hornet. Most of these wasps are solitary, and the social wasps comprise only about 1% of all the world’s wasp species. They’re mainly restricted to the subfamily Vespinae, which has around 11 members in the UK.

My recent sighting of the Saxon wasp came as quite a surprise to me. In the past few weeks I’ve been noticing more broad-leaved helleborines Epipactis helleborine (a species of orchid) than I usually do in my local area. They like to grow beside paths within woodland, perhaps due to the increased amount of light that reaches their leaves in comparison to the centre of the dense woodland. As a result, they are one of the most frequently encountered orchids in my region. However, despite their frequency, before I found my first Saxon wasp I had never observed any pollinators visiting these orchids.

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A spike of the broad-leaved helleborine on my neighbour’s verge

As you can see from the photo, their flowers are not particularly attractive colour-wise. Many other orchid species have evolved to mimic their pollinators, so that they are not drawn to the flowers by the promise of a meal but by the promise of a mate; as a bee, for example, attempts to mate with the flower of a bee orchid, pollination will take place. Moreover, the flowers emit a scent mimicking the pheromones emitted by the female bee, attracting the pollinating bees from far afield. This may sound clever, however reducing your number of pollinators to just one or a handful of species greatly restricts spread. Indeed, in southern England, the pollinator of the bee orchid is quite rare, and most of the time the bee orchid reproduces by self-pollination.

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The early spider-orchid, despite its name, has evolved to mimic the mining bee Andrena nigroaenea. I can’t personally see the similarity, but perhaps the bees can.

However, the broad-leaved helleborine does it slightly differently. Its primary pollinators are social wasps, such as the common wasp Vespa vulgaris (one’s standard picnic-botherer) as well as the Saxon wasp. Like many flowers it produces a nectar to entice the wasps in. However, once the wasps have arrived at the orchid flowers, they begin to become intoxicated by traces of opioids within the nectar. The narcotic-like qualities of the nectar cause the wasp to sleepily visit all of the flowers on the orchid multiple times, to ensure that all the pollinia from the flowers are transferred. I like to think that the opioids are also addictive to the wasps to encourage them to visit other broad-leaved helleborines, but I’m not sure whether this has been studied yet!

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A drugged Saxon wasp walking between helleborine flowers.

In the photo of the wasp above, it is quite easy to see a number of white objects on the face of the insect. These are the pollinia of the orchid, which stick to the face of the wasp after it has visited each flower trying to reach the nectar within. Each individual flower only has a few pollinia, which is the whole product of an anther. It is a coherent mass of pollen which is attached to the flower by a stipe (or stalk) and has a sticky disk on the other end which attaches to the face of the insect. Ideally, the insect then transfers these masses of pollinia to another plant, where the pollen in the pollinia will be transferred to the stigmata, completing pollination.

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The wasp reaching into a helleborine flower, looking for nectar. The pollinia can be seen just above the thorax of the wasp, attached to the roof of the flower, ready to attach to the wasp. 

It was fascinating to document this sighting, which was two firsts in one: my first Saxon wasp, and my first observation of pollinia in action. I’ll be keeping an eye on the helleborines this summer to see if any other wasps are enticed to the flowers by the sweet nectar and drugs!

Pan-species Listing: Top 15 New Species of 2017

2017 has been another fantastic year for me with regards to pan-species listing. I am pleased that I am continuing to add species even throughout the quieter months and although I am sure to slow down sooner or later as the number of species I can add is not infinite, I am still yet to break my steady stride. I have managed to delve into groups I haven’t tackled before such as lacewings and springtails. In this blog post I will list my favourite species added to my Pan-species List in 2017, out of about 700 added this year. If I have written a separate blog post about that particular species, the species name is hyperlinked to that post.

15. Marsh Frog

Adding new non-bird vertebrates is not easy, and so it was great to see several Marsh Frogs on a mid-June day at the nearby Warnham Local Nature Reserve. Although they’re non-native, they come in many different shades of bright green and so are much more attractive than the Common frogs!

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A couple of Marsh Frogs on the edge of a pool in the summer sunshine

14. Purple Toothwort

Plants are more regular pan-species listing additions for me, and although I’m still getting to grips with their huge diversity I have found that attending some Sussex Botanical Recording Society meetings throughout the year has been really helpful. This plant however was found in March, one of my earliest plant additions of the year, at Wakehurst Place. It’s one of several really fascinating plant species in the UK which lack chlorophyll to photosynthesise and therefore gain their nutrients directly from other nearby plants!

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A patch of the bizarre leaf-less Purple Toothwort, one of many found at Wakehurst Place

13. Waxwing

The winter of 2016/17 was one of the much hoped-for Waxwing ‘invasion’ years, and therefore it would be rude not to see some! The first flock I saw comprised over 30 birds, which is an amazing number for so far south in the UK. It was at a typical setting, an industrial estate! Waxwings often prefer these habitats because of the wealth of berry-producing bushes that grow there. I also saw a couple more later in the year, feeding in a Davidia (Paper Handkerchief) tree at Wakehurst Place, the fruits of which are large and kiwi-like. Very weird food for Waxwings!

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A Waxwing at Wakehurst Place, among the Davidia fruits.

12. Vestal

I have been moth-trapping in my garden for a few years, yet save for many Diamond-back Moths I hadn’t caught any migrants in my trap. Autumn presented a window of favourable air-flow from southern Europe and North Africa, which seemed likely to bring decent numbers of migrant moths to our shores. I put my trap out with anticipation on a couple of occasions that week, and on the second I caught exactly what I had been hoping for: 3 Vestals!

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One of the Vestals on the wall by the moth trap. They’re not the most attractive of moths but I was really pleased to see them!

11. Stemonitopsis typhina

I have very few slime-moulds on my list like this one, partly because they’re so tricky to identify. However this species, which I came across during a Sussex Fungus Group outing, was a great excuse to research their fascinating life cycle.

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10. Wryneck

In September, I was really lucky to be able to venture up to Spurn Bird Observatory in Yorkshire for the annual Migration Festival. Spurn is undoubtedly one of the major sites for rare birds in England and even quite early on in the vagrant season I managed to see brilliant birds such as Long-billed Dowitcher, Barred Warbler, Long-tailed Skua, Short-eared Owl, Caspian Gull, Roseate Tern, Black Tern, Little Stint, Little Gull, and one of my highlights, a Wryneck. This bird showed beautifully well, feeding on the cliff edge near the Sandy Beaches caravan site. It was so great to watch that I visited the bird three times over the weekend to take in the marvellously intricate plumage.

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Wryneck, taking a break from feeding on ants on the cliffside vegetation.

9. Cut-grass

This rather unassuming rare species of wetland grass has a deadly secret! Its blades are exactly that, as sharp as a knife. I didn’t want to test the sharpness on the Sussex Botanical Recording Society outing to Amberley Wildbrooks on which we saw it, however the blades are apparently able to slice through human skin thanks to the minute stiff hairs along the edges!

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Cut-grass: blades of steel

8. Devil’s Fingers

I’m sure that many people who are lucky to come across a Devil’s Fingers fungus by accident will not be certain that this intriguing organism is natural at all. It bears resemblance to an octopus that had been stuck into the ground upside down, with only its red tentacles emerging from the soil. Furthermore, the tentacles seem to have begun to decompose, with a foul-smelling covering of dark brown goo attracting flies that disperse the fungus’ spores.

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The Devil’s Fingers fungus that we came across on a Sussex Botanical Recording Society meeting at Chailey Common.

7. Green-winged Orchid

Orchids are surprisingly one of the groups that I haven’t seen many of. During the course of the year I added a few species, no rarities unless you count the Greater Tongue-orchids of dubious origin at Wakehurst Place. The Green-winged Orchid was my first orchid species of the year, at Danehill Churchyard. It was great to see the orchids with the nice church in the background, yet I think that the lawn where they were growing was scheduled for mowing. I didn’t have a chance to revisit to check if they were left alone or not, however hopefully they did have the opportunity to flower a little longer.

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A dark-purple Green-winged Orchid in front of Danehill Church. There were also light pink varieties present.

6. Beewolf

One of the highlights of my summer holiday was a two-day course led by Steven Falk on solitary bee identification at the fantastic Rye Harbour Sussex Wildlife Trust reserve. Of course, although we identified huge numbers of solitary bees, it wasn’t all about them on the weekend. We also came across a large wasp known as the Bee Wolf, which is the invertebrate equivalent of the wild canine. Females will catch adult Honey Bees and bring them back to their nest hole, where they will place the bees in a chamber. It’s within this chamber that the young Beewolf develops. At Rye Harbour, we were lucky to watch Beewolves excavating their nest holes and bringing Honey Bees into the chambers.

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5. Queen-of-Spain Fritillary

Birds are the group of organisms most likely to be associated with the word ‘vagrant’. However, during the summer a fortunate lepidopterist found no less than three Queen-of-Spain Fritillaries on his transect near Peacehaven, a species that is unable to breed in the UK as they can’t survive the cold winters. They are therefore very rare summer visitors at best. I am very grateful to the farmer Colin Appleton for allowing lots of keen naturalists onto his land to watch these three regal butterflies ‘lekking’ around a bonfire. Although they apparently travel in groups, explaining why three arrived at once, they are very territorial and the bonfire was the central spot for their territorial disputes, like a boxing ring.

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One of the Queen-of-Spain Fritillaries basking in the sun near the bonfire.

4. Moon Carrot

This wonderfully named plant is not very distinctive, looking very similar to more common umbelliferous plants such as hogweed, yet it’s rare nationally. To make up for its likeness to the other members of its family, it has chosen a spectacular site at which to grow. What seems to be the only modern site for this species in Sussex is the cliffs at Seaford, near the Cuckmere. Some individual plants grow right on the cliff-edge, and look marvellous with the Seven Sisters cliffs in the background. They’ve even made the cover of the new Flora of Sussex!

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The Moon Carrot is so-called as it apparently glows in the moonlight!

3. Wood Warbler

I loved listening to a male Wood Warbler sing its heart out at an undisclosed site in Sussex this year, although it was quite a sad experience. This was the first Wood Warbler on territory for 3 years in Sussex, a county where it once used to be a regular breeder. The energy the warbler put into its song was incredible, for weeks it would sing as loud as it could non-stop while hopping tirelessly from tree to tree. Yet due to the species’ rare status in Sussex these days, there was never a female to respond.

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A brief pause from what must be absolutely exhausting for the Wood Warbler

2. Lesser Glow-worm

Of all the species included in this top-15 blog post, this one is my most recent find. In fact it was just before Christmas that I found a beetle larva beneath a log at Hedgecourt NR. I sent it to Max Barclay, the beetle curator at NHM London asking what it could be as I was stuck. I had only managed to find one possibility, Phosphaenus hemipterus or the Lesser Glow-worm, however I doubted it was that as it is the rarest of all the glow-worms found in the UK. As far as I know there is only one known modern-day colony in the whole of the country, at a site in Hampshire. To my surprise Max kindly replied saying that he did think it was indeed a Lesser Glow-worm, and he had even received confirmation from another expert on glow-worms! Now we’re just waiting to hear back from some specialists in the Czech Republic before we can be 100% certain, yet it certainly seems highly likely I’ve found quite a rarity!

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Despite a thorough search of around 20 logs a few days later, I was unable to find another larva.

1. Wart-biter

At number one, the Wart-biter must be one of my favourite finds from this year. It’s a massive, elusive bush-cricket that’s hard to find at only 5 known modern-day sites in the UK. I visited one of those sites, Mount Caburn on the South Downs, with the Amateur Entomologists’ Society in August specifically to look for this species. The easiest way to find them is to listen for the stridulation (singing), however they only stridulate on warm, calm days and there was a heavy band of rain moving in. I decided to use the highly sophisticated technique of walking around and hoping to chance upon one and it worked! A female jumped from my feet as I was walking, to land in a perfect position for all of the attendees of the field meeting to get an excellent view.

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The Wart-biter gets its name from the old Swedish method of getting rid of warts: allowing this cricket to bite them off!

There concludes my top-15 pan-species listing additions of 2017. It was very hard to condense all the brilliant finds into just my 15 favourites, this blog post could easily be 10,000 words long.

 

 

Photo-Stacking at the Angela Marmont Centre

On Wednesday I was very lucky to be able to visit the Angela Marmont Centre at the Natural History Museum in London. The Angela Marmont Centre for UK Biodiversity is an amazing place for naturalists in the United Kingdom that is available for anyone to use. With such a range of resources such as the photo-stacking equipment; a huge library; and the whole of the British collections, it really is invaluable.

I have used the photo-stacking equipment here once before and I really do think it is a very clever piece of kit. It takes lots of photos (I took around 65 for each specimen) all at different focal points and then merges them together using software called Helicon Focus. With all of the different focal points on the specimen covered, there is no part of the specimen that is out of focus and it is all very sharp. This produces a clear image that can show many different features, excellent for identification or illustration of species.

I think that photo-stacking is incredibly useful for a number of projects. For example, if you were writing an identification guide and space was limited, you could in many cases show all the features of an organism in just a single photograph. Also for illustrating an article or a short piece of writing where there is a limit to the number of photographs, you could include just a single image with all of the key features clear and visible.

Below are a few of the photo-stacked images that I took using the equipment. You can find all of the images of the identified specimens on this page. I still have some photographed specimens that I need to identify, and I will post them on that page once I have put a name to them.

Stenodema calcarata labelled

 This Mirid bug is just 8mm from head to end of the abdomen. Its distiguishing feature is the two short spines on the hind femur. This separates this species and the very similar Stenodema laevigata.

 

 

Poecilus cupreus labelled

This is the largest specimen that I photographed, 13mm. This rather big Carabid beetle was swept from a patch of nettles, much to my surprise!

Agriotes pallidulus labelled

This is a very small Elaterid, or click beetle, only 4mm long. When they are threatened they often roll onto their backs and catapult themselves upwards to escape predators and they make a ‘click’ sound as they do so.