Thursday, 29 June 2017

Invertebrates, June 2017

June was a generally a very dry month which included a two week spell of very hot weather, with temperatures reaching 30'C on several occasions in the middle of the month. At times it was almost too hot for invertebrates, and during the hotest periods there was clearly a midday lull in hoverflies in particular.

It was the month that the impressive bumblebee mimic hoverfly Volucella bombylans appeared in numbers. My first of the year was at Pennington Flash, but soon they were a regular feature everywhere. Like Merodon equestris, this species can mimic more than one species of bumblebee. The form in these photos resembles Bombus lucorum, the white-tailed bumblebee. Interestingly, the larvae even live in the nests of bumblebees, feeding on the debris at the bottom of the nest.

This is also Volucella bombylans, of the mainly black form with a red tail which resembles Bombus lapidarius, red-tailed bumblebee.

Amongst the many highlights in June, finding the Currant clearwing moth Synanthedon tipuliformis on currant bushes in my back garden must rank amongst the best. Clearwing moths are day flying and mimic wasps. They are often thought to be best seen by the use of pheromones which attract the males, but although I have used lures to see these insects in the past, I have also seen at least three species of clearwing simply by looking in suitable habitat as I did in this case.

Currant clearwing with a currant!

Silver-studded blues Plebejus argus were out in their hundreds on the Great Orme, Llandudno in the middle of the month, these two males were on common rockrose.

The Volucella hoverflies are amongst the largest and most impressive in the UK, this is the largest of all, the hornet mimic Volucella zonaria, photographed on bramble in Aylesbury, Buckinghamshire.

Xanthogramma pedissequum, Arnside Knott. A wasp mimic hoverfly.

Ferdinandea cuprea. This actually looks like a fly mimic hoverfly, but I can't think why a hoverfly (which is just a type of fly anyway) would want to mimic a fly.

Scaeva pyrastri is a migrant hoverfly which like the red admiral and painted lady butterflies is present each year in the UK in variable numbers. This individual was photographed at Burton Mere Wetlands. Note the unusually bulging frons which is a feature of this species.

Volucella pellucens, great pied hoverfly was recorded at many sites in June.

Chrysotoxum arcuatum, another wasp mimic hoverfly at Arnside Knott. This is one of a group of five hoverflies which are difficult to seperate in the field. However on range alone four of the five can be eliminated, since they are more southerly species. Also a feature of Chrysotoxum arcuatum is that the 3rd antennal segment is longer than the first two combined, a feature which can clearly be seen in this photo.

Another one of the difficult five, this is Chrysotoxum cautum photographed in Aylesbury. Note the differences in antennal segmants to the previous hoverfly, with the third antennal segmant shorter.
Range again can also be used, this time to rule out  C. arcuatum, which is a north-westerly species in the UK, with very few recorded occurances in Buckinghamshire.

Microdon myrmicae/mutabilis at Arnside Knott. This is most likely M. mutabilis from the habitat, but it is impossible to split these two species at the adult stage. The larvae live in ants nests.

Merodon equastris, another bumblebee mimic hoverfly.

This is one of the best marked Eristalinus sepulchralis I've ever seen. The lack of dull patches on the glossy looking abdomen, and the fact that it was on the saltmarsh at Leighton Moss point to it being possibly E. aeneus, but enquiries on the Facebook group UK Hoverflies suggest that it is more likely E. sepulchralis. This is another species of hoverfly which appears to be mimicking a fly.

One of several very similar honey bee mimic hoverflies, this is Eristralis horticola. This is a bright looking Eristralis with a dark mark in the centre of each wing.

Eristralis arbustorum, the main identification feature is the unmarked face. Most other similar Eristralis have a dark line running vertically up from the antennae.

Parhelophillus species are very difficult to seperate  and this particular individual can only be called Parhelophillus sp.

However this is a male Parhelophilus frutetorum, identifiable by the long-haired tubercle on the hind femur. On hogweed at Pennington Flash.

This, on the otherhand, can safely be called Parhelophilus versicolor, since the male clearly lacks  the tubercle.

The micro moth, Olethreutes arcuella.

Semaphore Fly Poecilobothrus nobilitatus. This is the male in Dingle Gardens, Quarry Park in Shrewsbury.

The male semaphore fly flicks it's wings at the female in display, hence its name.

Hydrometra stagnorum, water measurer, Sorrowcow pond, Pennington Flash.

Pirata piraticus, a pirate spider carrying its babies on its back, Sorrowcow pond, Pennington Flash.

This photo was taken in County Tyrone, Northern Ireland. This four-spot chaser had flown into the web of the spider, Larinioides coruntus. I would never have believed that just a few strands of web would be capable of holding such a large and powerful predator as this chaser, or that the spider would even consider approaching such an intimidating insect, but the web held and the spider kept its nerve and proceded to spin more web around the dragonflies wings and legs, before killing it by biting it in the abdomen as you can see here.

Ramshorn snail, Sorrowcow pond, Pennington Flash.

The day flying moth cistus forrester Adscita geryon was out in good numbers on the Great Orme in mid June.

Nemophora degeerella

And finally......

Just when I thought that invertebrates were done for the month I was sitting in the middle of a barley field in rural Buckinghamshire at dawn, doing bat emergance survey, when I spotted this guy roosting on top of a culm of barley. It's a purple hairstreak butterfly, surely the most unlikely creature I have ever encountered so far on a bat survey!

Wednesday, 28 June 2017

Relieving the cabin fever at the Nene Washlands

I seem to be spending most of my time during the week these days ensconsed  in a hotel in bird free deepest Buckinghamshire. Everytime I check Birdguides / Nearby it tells me there's a Quail still singing at some RSPB reserve I've never heard of in a county called Oxon, wherever that is. Sounds like it should be somewhere near Oxford. Surely that would be Oxfordshire though? Anyway there's never anything else reported on Birdguides, it's been that way for three weeks now and I'm not confident it's going to get any better in July. Birds just don't exist in this part of the world at the moment, and I can't even look for inverts this week, with the sun now a distant memory and dull drizzly weather day after day. I feel like I'm getting the Premier Inn version of cabin fever, so allow me at least this indulgence.

Today, just for laughs, in an attempt to inject some excitement into my week and faced with the prospect of another afternoon in the hotel room, I decided to head up to Northampton and have a look for the female bufflehead which has been at Clifford Hill Pits on the Nene washlands. This is a large flood defence system, similar to Hesketh Out Marsh or Donna Nook, the difference being that it's inland, but it serves much the same purpose, designed  to relieve the pressure on Northampton and surrounding area should the River Nene flood. The bird has received scant attention so far from birders, partly because of the time of year I guess, but also because it's sporting a metal ring on its right leg.

Ducks seem to be guilty until proven innocent these days, the attitude seems to be, if it's wearing a ring it must be an escape, yet the reality is, thousands of wild ducks are ringed every year, including buffleheads, and in fact the ring may ultimately prove it to be a genuinely wild bird. Perhaps somebody has read the ring, but I don't think so. Unless people try we'll never know. Anyway I decided to give it a go, because I was bored and I've never seen one in the UK before so let's call it an insurance tick, plus I'd never been to the Nene washlands before so it was a new site tick, which is always worthwhile for future reference.

I'd gleaned a few site instructions from Bird Forums so I had a reasonable idea how to find the place, but I wasn't prepared for the scale of the washlands. Obvious I suppose really, if you're going to build a flood defence system it needs to be big, but this really is on Hesketh Out Marsh scale, possibly even bigger. Anyway, to sum up it was a hell of a walk. The place where the bird had last been reported was actually close to the entrance, but I couldn't find it, and in the end I walked all of the way round. I'd more or less given up, but decided that it was either go back to the misery of the hotel room or keep trying. I walked over again to where it had last been reported, and guess what?  There it was. It must have thought that I needed the walk when I went past first time, which is probably true.

Fortunately I'd inadvertently managed to "trap it" in a narrow part of the lake so it couldn't swim very far away from me and I fired off a few photos, but it was very nervous and after a few minutes it took flight for 100m, joining a small flock of tufted ducks. It was very nervous..... I've seen them much closer in Central Park in New York, where they also seem tamer. Not that tameness proves anything one way or the other.

Before I saw the bird, I'd had the vague hope of reading its ring through the scope but there really was no chance of that today. Hopefully somebody else will manage to read it or better still photograph the ring on a better day. Surely it's worth the effort? Oh well, excitment over, time for another pub meal.....

Monday, 19 June 2017

The Magnificent Great Orme

The Great Orme at Llandudno is one of my top 10 favourite places in the world, and June is one of the best months to visit. Not only does it have breathtaking views comparible with anywhere you might like to mention, it also has an array of flora and fauna to keep the naturalist happy for days on end.

Today we parked at the West Shore and walked clockwise around the Orme, taking the track up and over the limestone pavement from Llys Helig to the Rest & Be Thankful cafe, and then following marine drive back to Llandudno.

Almost immediately it was obvious that there had been a mass emergance of the butterfly silver-studded blue. They were everywhere, hundreds of them, on the roadside verges, in the gardens, even landing in hedges or on the road itself.  To see them at their best though you need to get onto the limestome grasslands where the perfect photo opportunity is to get them feeding on common rockrose, a limestome loving plant that flowers on the Orme in profusion at this time of the year. I've never seen silver-studded blue in such numbers anywhere before, and it was worth the walk just to experience this spectacle.

Male silver-studded blues on common rockrose.

A female silver-studded blue.

These grassy hillsides on the west side of the Orme are the best places to see silver-studded blue in my experience.

The views of the Conwy estuary ain't half bad from here either!

A little higher up we came across lots of the day flying moth, Cistus forester. This is quite a scarce species in the UK, and is usually found where it's favourite food plant common rockrose grows. Although there is plenty of common rockrose at lower levels, in my experience this moth is best seen on the Orme on the grasslands either side of the limestone pavement.

Common rockrose Helianthemum nummularium.

Superficially similar, but this is a much rarer plant. Hoary rockrose Helianthemum oelandicum is a speciality of the rocky Welsh coastline wherever there is limestone, but it is seen at its best on the Great Orme.

Hoary rockrose.

Hoary rockrose.

Another rarity of the  Great Orme limestone grasslands is Spiked speedwell Veronica spicatta.

The Rest & Be Thankful cafe is a good place to stop and refuel for a while, before continuing the journey down Marine drive and back to Llandudno. I like walking back down Marine Drive because offers a whole array of different plants growing on the limestone cliffs.

One of the most striking and beautiful of plants in June is bloody cranesbill Geranium sanguineum, a real limestone specialist which is common along Marine Drive.

Red valerian Centranthus ruber is an even commoner plant of the limestone cliffs.

Grayling butterfly on Red valerian.

The views on this side of the Orme aren't too bad either. The main seabird colonies are on this side of the Great Orme, and include many hundreds of guillemots, razorbills, kittiwakes, cormorants and fulmers. A more recent arrival is the chough, which now breeds on the Orme and today we saw about 10 during our walk along Marine Drive.

As you walk along Marine drive you can sometimes come across seepages in the limestone such as this. The solubility of limestone in naturally acidic rainwater over millions of years results in the caves, pot holes, underground rivers and grikes often found in limestone regions. Where water runs down or through limestone, organic acid from the soil above increases this action and in caves can form stalactites and stalagmites.  The rock in this photos looks like it is melting, and you can see what looks like a mini stalactite forming. The rock here is soft, almost like mud to touch, and virtually no plants can tolerate living in such a calcareous position, not even bryophytes. Yet if you look over to the left of the photo and you can see that there is a small plant growing and that it is almost covered in the limestone solution! How can this plant survive here when others cannot?

The answer is that it is a butterwort Pinguicula vulgaris, an insectiverous plant which derives most of its nutrients from small insects which stick to its leaves and are then digested. In an environment such as this the plants roots are pretty much used just to anchor it down.

The Orme always offers something unexpected, and today it was this pyramidal orchid Anacamptis pyramidalis growing next to the road on Marine Drive. I don't think I've ever seen this orchid on the Orme before.

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