Category Archives: Diptera – two winged flies

Welcome house guests

One day in the summer I noticed a crane fly sitting on the outside of a window so I grabbed my camera with the macro lens and went on a bug hunt round the house. And these are the beasties I found lurking:

Male house spider, Tegenaria gigantea, with a glint in his eye

It was a murky day so the pictures I took in the house required the flash, so I experimented with the flash power, the ISO, and used the smallest aperture I could to maximise the depth of field (DOF). The ones I took through the window didn’t require the flash, but I kept the ISO higher, again so I could maximise the DOF:

Crane fly or daddy longlegs, Tipula paludosa, revealing one of the more bizarre head designs in the animal kingdom

On the same window as the crane fly were a number of garden spiders (Araneus diadematus) including this male:

The same male garden spider wrapping up a hoverfly

The crane fly was playing a dangerous game running the gauntlet of the garden spiders but it managed to avoid getting eaten. The garden spider above was on the window for weeks and was rather larger at the end, demonstrating that ambush predation is a highly successful strategy when combined with a sophisticated web to ensnare the prey.

Female oak bush cricket, Meconema thalassinum

It’s not uncommon in the summer for oak bush crickets to appear in the house and there’s no mistaking this creature. the one here is a female which is immediately apparent from her long ovipositor protruding from the back end. They are common all over the south of England and are carnivorous, feeding on small insects, so they’re welcome in the house.

And another carnivore which I’m happy to provide accommodation for is the daddy long legs spider:

Daddy long legs spider, Pholcus phalangioides, with a few of her many offspring

The daddy long legs spider looks so delicate but is a voracious predator and will catch and eat the much chunkier house spider as well as its siblings!

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Cheap and cheerful

Last year when I changed my old Nikon D40x for a Nikon D7000 I also bought a cheap second hand Sigma macro lens to go with it. I wouldn’t normally do that, but because of the attractive price tag I thought I’d give it a go in order to dip my toe in the water of  macro photography without upsetting my bank manager. Or, more importantly, my wife!

When I first got the lens I mooched around the house looking for small things to photograph and I didn’t have to wait long before a selection of arthropods presented themselves.

Vespula vulgaris, I also like this image because of the clear double reflection in both panes of the double glazing.

The wasp was buzzing up and down the glass of a door trying to find a way out so I practised my macro technique on it before opening the door and providing it with an escape route.

Even though the head is not in sharp focus I also like this image because of the reflections in the window glass

In this image the plane of focus has captured the wings and the head is slightly out of focus, demonstrating the narrower depth of field (DOF) inherent with macro photography. Tech note: DOF decreases in range with magnification and aperture, so for a given aperture the DOF will decrease with increasing magnification. Or put another way, if you need to open the aperture wider (smaller F-stop number) to get enough light on the sensor to generate an image, you may need to sacrifice some magnification.)

And while I was busy with the wasp a house spider appeared by my feet so I had a shot at that too:

Young house spider, a species of Tegenaria. Despite the size and speed, their bite, if not their induced terror factor, is harmless to humans

This individual was only 2-3cm long indicating it’s a young one and from the shape of its abdomen it’s a male. The female is bigger and has a more bulbous abdomen.

And on an earlier occasion, whilst fulfilling my domestic obligations and doing the washing up, this splendid red eyed dipteran appeared on the teapot on the kitchen window sill and sunned itself for long enough for me to grab the camera and snatch a few close ups.


I don’t know what species the fly is but if anyone is able to enlighten me I’d be very grateful. And it added an enjoyable interlude to the washing up too!

The lens I bought was the Sigma 70-300mm APO DG 4-5.6 macro zoom which can switch to macro between focal length 200-300mm. It has pretty solid build quality, it’s reasonably small (although it gains approximately 5.5cm in length at 300mm zoom) and is a pretty good little lens for general purpose zooming too.  It’s noisy and slow when moving from far away to close in, and vice versa, but as you can see I’ve had some fun with the local insects, and although I need a lot of practise it holds the promise of lots more minibeast shots. All in all it was a good ninety quids worth, and I shan’t be rushing out to spend lots of cash on a better quality lens just yet because I don’t think I need one. I shall carry on having fun with this cheap and cheerful one.

 

The birds and the bees

Insects have been hit hard by climatic aberrations in recent years and on my meanderings around the Cambridgeshire countryside this year numbers of bees and butterflies sightings have been down compared to previous years. It’s now the middle of June and I saw the first dragons of the year today; two damselflies. I also read this week in ‘The Guardian‘ newspaper that a third of managed honeybee colonies in the USA were wiped out in 2012. This article makes very sobering reading. And it’s a similar story in Europe, but in Europe neonicotinoid pesticides, which have been implicated in colony collapse disorder, have been banned for two years to evaluate their effect on honeybees. My concern is that the onslaught on the bees is complicated and removing one variable may not show a significant effect in the limited two year duration of the ban. But I hope it does!

Early last month the sun finally broke through and gave us some insect friendly weather and it was remarkable how quickly the microfauna emerged.

Beefly – Bombylius major

Beeflies are found over large parts of the globe and can be seen hovering in sunny glades from the springtime. The narwhal of the Dipteran world, the spike looks fearsome but is only used to probe flowers for nectar, there is  no sting. Beeflies procreate by flicking their eggs into the entrance to the burrows of wasps and bees where the larvae feed on the grubs of the occupants.

A pair of hoverflies doing their best to rectify the decline in the insect population

I think these hoverflies are ‘Eristalis pertinax’ but I’m not certain. It was good to see them though, especially as they were taking their biological responsibilities so seriously.
Addendum: on the subject of climatic aberration mentioned at the top of this post I just found and read with increasing concern this link:

http://robertscribbler.wordpress.com/2013/04/12/human-climate-change-is-wrecking-the-jet-stream-uk-met-office-calls-emergency-meeting/

which my blogging buddy Sam posted on her excellent WP blog ‘Science on the Land‘. This provides a chilling insight (in every sense) into why the weather in the northern hemisphere is behaving the way it is. And it doesn’t look as though it’s going to get any better folks.

Anachronous insecta

A few posts ago I showed you some of the spider I encountered in the short spell of good weather we had in the late summer and early autumn. I think maybe some species were making hay whilst the sun was shining because there were also a lot of hoverflies around at that time too. And here are  three of the species I found. It’s the wrong time of year to be posting about hoverflies, hence the title of the post, but I haven’t been able to get out with my camera so I reckon a hoverfly post is better than none at all! Identifying hoverflies can be tricky because there are species which look very similar to each other and I’m no expert, so I hope my identifications are accurate but if any of you spot an error please let me know.

Eristalis tenax

Eristalis tenax is a type of hoverfly known as a ‘drone fly’, so called because they mimic honey bee drones. They are common throughout the UK and the females, which mate before overwintering and laying their eggs in the springtime, can be seen in any month of the year because they emerge from hibernation to feed when the weather warms up sufficiently. The larvae of this species are called ‘rat-tailed maggots’ and feed in sewage outflows and rotting carcasses – the more putrid it is the more they seem to like it! They are aquatic and the reason they are called ‘rat-tailed’ is that they have an extendable tube which can protrude up to around 5cm which they poke out of the water and use to breath air.

Tapered drone fly – Eristalis pertinax

The tapered drone fly is so called because the male has a tapered abdomen which is visible on this individual. It is otherwise a similar species to E. tenax and it’s larvae are also known as rat-tailed maggots. Apart from the taper it’s also distinguishable from E. tenax by it front legs which are pale.

My favourite hoverfly I found this year is this one:

The footballer – Helophilus pendulus

It’s called ‘the footballer’ because it’s colours are likened to a football shirt. It’s scientific name means ‘dangling sun lover’. The larvae of this species feed on detritus and have been found in wet manure, drains and in very wet sawdust. It’s widespread throughout the UK and can be seen throughout the summer in bright sunny locations in hedgerows. Despite the unsavoury but indispensable habits of the larvae of all of these species they transform into the most handsome adults.

I haven’t done a dedicated Christmas post this year so here’s wishing you all a very merry Christmas and a happy and healthy 2013!

Correction – Volucella zonaria

In my post ‘Backyard Safari‘ from September 15th I included this photograph of a magnificent hoverfly which I identified as Volucella inanis:

I subsequently received a comment from Roger Morris of the Hoverfly Recording Scheme (HRS) to let me know that I had incorrectly identified the fly and it is in fact Volucella zonaria. So thanks to Roger for putting me straight.

When it appeared in my garden I mistook it for a hornet, it’s our largest hoverfly and I’ve seen it described as a ‘hornet mimic’. The adults feed on flowers such as buddleia which may be why it appeared in my garden, and the larvae feed on the detritus which accumulates in the cavity at the bottom of wasp nests. It wasn’t recorded as resident in the UK until the 1940’s when it appeared around London and then spread across the south of England to the west country. It’s population is still most dense in the south east but it is regularly recorded in the east Midlands with occasional recordings in the northwest of the country.

Back yard safari

A couple of posts ago I described my Fenland safari and since then I just happened to have had my own ‘back garden safari’! Lots of colourful creatures have been stopping by to refuel.

I’ve previously expressed concern for the depleted populations of insects, in particular butterflies and dragonflies, due to the mad weather we’ve experienced in the UK this year, but in the last couple of weeks there have been some great sightings outside my back door.


Common darter (Sympetrium striolatum) female perched on the clothes line

The dragons have been late to appear but since the last week in August there have been common darters regularly alighting and migrant hawkers hunting overhead.

And of course it’s that time of year when the arachnids are most in evidence, and my garden is festooned with garden spiders, there are webs attached to every surface: walls, plants, windows… everywhere.

Garden spider female, Araneus diadematus, despatching her prey, a small fly

The female garden spider has a bulbous abdomen which is adorned with the fabulous diadem that gives the species its name. The male is smaller than the female and has a flatter, kite shaped, abdomen, but he also carries the diagnostic markings. A couple of years ago I posted about the perilous love life of the garden spider, suffice to say the sex life of the male can be dramatically and terminally curtailed if he fails to show the lady sufficient respect!


This garden spider male set up home inside the bedroom window – until  the resident arachnophobre found him and relocated him

As well as the spiders, the occasional cricket strolls by, and this little chap was taking shelter under a sunshade from the unseasonally hot weather last weekend:


Oak bush cricket – Meconema thalassinum – the male of the species. The female has a long, upturned ovipositor protruding from her rear

The oak bush cricket is quite a small example of the genre, they are 13-17mm long and are carnivorous, feeding on small insects. They live on the edge of woods and in gardens and appear from July into the Autumn.

Also putting in a welcome appearance was a common buzzard, Buteo buteo:

The buzzard has been one of the birds which has really bounced back since the more stringent controls on of agricultural pesticide use were introduced in the 1980’s. I’d never seen a buzzard until I was in my 20’s and even then it was the occasional sighting in the wilds of west Wales or down in Cornwall. But they can now be seen over all of England – even from my garden.

Hoverfly – Volucella inanis

Hoverfies rarely have common names, they’re simply known under the generic name ‘hoverfly’. And V. inanis is no exception, at least as far as my research reveals. There was great excitement when it first buzzed into the garden because at first glance we thought it was a hornet due to it’s size and its yellow and red colouration. And it was a whopper! They can grow up to 15mm long and this one was one of the bigger ones. It eventually settled and posed rather obligingly on the edge of the rabbit run while I snapped a portrait, and it is a very handsome fly. It has an interesting breeding tactic too laying its eggs in the nests of other social wasps, including hornets – which probably explains its size and colour scheme – where they hatch and feed on the larvae of the host.

Comma – Polygonia c-album

I waited expectantly for this comma to open its wings and show the gorgeously ragged orange symmetry, but it didn’t. So I had to content myself with this silhouette of it perched on a cooking apple.

Insects and molluscs

Over the last couple of weeks I’ve been out and about photographing wild flowers, and of course the raison d’etre of flowers is to produce the reproductive cells of the plant in order to ensure survival. And as plants are immobile they rely on other vectors to connect the male and female parts, that can be the wind and the rain but many flowers are exquisitely evolved to attract one or more species of insect to carry the pollen to the ovum and effect fertilisation.

So in the course of photographing the flowers some of them were hosting a pollinator or two:

Tree bumble bee – Bombus hypnorum

This tree bumle bee was sipping nectar from the flower of the white deadnettle. It’s one of the insects that is strong enough to get to the back of the flower and take the nectar. Flowers have evolved in this way such that the insects have to pass the stamen, which is where the pollen, or plant sperm, is produced. The stamen is made up of the filament and the anther, and foraging insects brush against the anther picking up pollen which they carry to the next flower where it is deposited on the female part of the plant – the ‘carpel’, and fertilisation ensues.

There are various species of bees in the UK but only around half a dozen common ones. Bees are in trouble in this country and no one seems to know why, both honey bees, which live in colonies, and solitary bumble bees are dying out at an alarming rate.

Buff tailed bumble bee – Bombus terrestris

The buff tail above was in a particularly poorly condition and had tiny mites crawling on it’s body so I imagine it didn’t do much more pollinating.

Soldier beetle – Cantharis rustica

The soldier beetles are related to the fireflies and they get their common generic name from one species which is bright red and is therefore named after the ‘redcoats‘ – English soldiers from days of yore. The larvae and the adults are carnivorous, the larvae feeding on insect eggs and caterpillars and the adults on aphids. They also feed on nectar and can therefore pollinate too.


Black slug – Arion ater

Alot of people have an aversion to slugs because of the damage they can do to fruit and vegetables, but this chap was out in the field making a meal out of a couple of dandelion seedheads. I don’t think they contribute much to pollination and they are predated by frogs and toads and also hedgehogs. Although I’ve heard that if too much of a hedgehog’s diet consists of slugs, parasitic worms living in the slugs can get into the lungs of the hedghog and kill it because its lungs fill up with fluid. Which sounds pretty unpleasant but I guess it’s not the fault of the poor old slug!


Brimstone moth – Opisthograptis luteolata

The brimstone moth is a splendid creature with a wingspan of 32-37 mm. It’s common and widespread across the UK. In the warmer climes of  the southern UK there can be three generations in a year but in the north there is only one brood per annum, and adults can be seen on the wing between April and October. The caterpillars feed on various trees and bushes including hawthorn and blackthorn.

A couple of weeks ago after days of rainfall which had moistened everything I found a 50m stretch of verge which was crawling, literally, with hundreds of yellow and brown snails.


Brown lipped snails – Ceppaea nemoralis. Just a few of the hundreds that were making the most of the damp conditions

The ‘lip‘ of the snails in their name is the front edge of the shell which can be seen in the next two pictures and is lighter brown on the yellow one and a much darker brown on the brown one:

Snails are predated by songthrushes. They pick up the snail by the fleshy part and crack the shell on a handy stone. Some years ago I was sitting at home on my own reading a book and everything was very quiet. I heard ‘tap tap tap’ on the front door, but when I went to answer it their was no one there. So I went back to my book. A few mintes later I heard the same tapping and again there was no one there, so I opened the door to have a look up the street and rather than a visitor there was a collection of broken snail shells on my front doorstep. It transpires the tapping I’d heard was a songthrush using my front doorstep as an anvil to swing the snails against and hammer open the shells!

Birds and bee(flie)s

The day after the cold weather put paid to my snake hunting exploits I decided to take the dog for a quick run in the afternoon. He had just had a small tumour removed from his back leg and so he had a lampshade on his head to stop him chewing his stitches and consequently this walk was only meant to be a short one, and I wasn’t even going to take my camera. But on the way out the door I decided because it was very sunny and very warm I would take my camera. And I’m glad I did because there was wildlife in abundance.

Peacock butterfly, Inachis io, sunning itself on the path

The air was abuzz with insects including butterflies. I really like photographing butterflies and peacocks are good because they present a medium sized challenge. If you approach with stealth and don’t cast a shadow on them they let you get to within a few feet. The peacock is a species that can be seen at any time through the winter as it can wake in response to warmer weather, but they emerge in spring around the end of March/beginning of April, so the timing for this one was spot on.  As I was photographing the peacock a sparrowhawk (Accipiter nisus, Dansk: spurvehøg) flew past at high speed, much too fast to enable a usable photograph, it’s always good to see a bird of prey because I think it suggests the prey species are in good order too.


Long tailed tit, Aegithalos caudatus, Dansk: halemejse

The field where I found the peacock butterfly has a corner which faces south west and it was sheltered from the wind and bathed in spring sunshine. It was really warm when I arrived there, so I stood still and watched and listened while the dog went off to explore, and the trees around were full of birds including the long tailed tit, above, and a song thrush, below.

Songthrush, Turdus philomelos, Dansk: sangdrossel

While the birds were capturing my attention in the trees, butterflies weren’t the only insects there. In my corner there were also beeflies buzzing around. I was keen to try to photograph them in flight which is a tad more challenging as they would hover for a few seconds before darting off at very high speed in zig zag lines. But they were making the most of the shelter from any breeze that prevailed in this sheltered spot and I spent a good hour trying to photograph them.


Beefly, Bombylius major

The beefly, as the name suggests is a bee mimic. It has a very prominent proboscis which is used to extract nectar, and the fur is part of the bee disguise. It is a very good pollinator but is detrimental to other pollinators.

It is detrimental because it parasitises other bees and beetles. And the way it achieves that is another of those bizarre evolutionary adaptations that even the most imaginative science fiction writer wouldn’t dream of. It mimics bees in order to get close to their burrows where using its legs the female will flick her eggs into the hole where it hatches and attaches itself to the host. Then the gruesome bit: it lies dormant until the host commences pupation and then becomes an ‘ectoparasite‘ which means it remains on the outside of its host but extracts the body fluids to fuel its own growth. After draining its host dry it reaches the pupal stage which can vary hugely in length and they have been known to overwinter before emerging as an adult the following year.

Beeflies have appeared in several blogs in the last week or so and there are some more very fine images here:

http://www.leavesnbloom.com/2012/04/bombylius-major-bee-fly-aerodynamics.html

Rosie from ‘leavesnbloom’ has a wonderful collection of images of Bombylius major and Harlan from ‘The Roused Bear’ has also captured one in Iowa in the U.S.:

http://therousedbear.wordpress.com/2012/04/07/a-fuzzy-bee-fly/

They can be found across the whole planet except Australasia.

More birds which appeared in the trees around while I was chasing beefly were the common or garden greenfinch and chaffinch:


Greenfinch male pecking at a twig
Chaffinch male just taking it easy

Both greenfinch (Carduelis chloris, Dansk: grønirisk) and chaffinch (Fringilla coelebs, Dansk: bogfinke) are common or garden, but are both beautiful birds, and they can be seen here in the U.K. all year round. But a species that isn’t here all year round and returns after its winter migration to north Africa is the chiffchaff (Phylloscopus collybita, Dansk: gransanger):

The chiffchaff, named after its characteristic song, is a warbler and despite being a small bird they are tough. Their migration takes them south across mainland Europe, across the Mediterranean Sea and into north Africa, to retrace their flight four or five months later in the spring. And despite the hardships associated with such a gruelling endeavour, according to the British Trust for Ornithology (BTO), there are around three quarters of a million territories in the UK. They are one of the first migrants to arrive back in the U.K. and can be heard singing as early as late February. But this my first one in Cambridge on the first weekend in April.