Wednesday, June 30, 2010

Red, Yellow and Blue


There a few spectacles in the British countryside that rival a field of poppies in full bloom. There are two fields at Warkworth on the Northumberland coast that are currently ablazed with these scarlet flowers. Like many plants, poppies produce seeds that can remain dormant in the soil for decades. They require light for germination, so only burst into life after they’ve been brought to the surface by the passing of a plough. Poppies belong to a group of arable weeds that includes corn chamomile, corn cockle, corn flower, corn marigold, bugloss and henbit whose flowering depends on regular soil disturbance, so they have always been a feature of agricultural landscapes since farming first began. In Victorian times all these species were very common, but the development of efficient seed cleaning technologies for cereal crop seed production and the advent of effective modern herbicides have removed them from fields so efficiently that many are now rare. Poppy’s vast seed output has been its salvation. Poppies survive seed burial for long periods and are often revived temporarily when new roads are cut through former agricultural land, or when grassland that was long ago planted with wheat and barley is freshly ploughed.


Behind the dunes at Warkworth, about half way to Alnmouth, there's currently another wonderful floral display in a patch of swampy ground. A single yellow flag iris (above) is a thing of beauty, but half an acre of them in full bloom is something else.......



And a little closer to Warkworth, in a corner of a field that has been left unplanted, there's the most stunning display of bugloss, a cornfield annual that occurs sporadically in the North east but here grows in such abundance that about a quarter of an acre is tinted with forget-me-knot blue.


We lament the fact that some individual wild flower species are becoming rare, but it's even more regrettable that massed floral spectacles like this, once common, are now few and far between...

Tuesday, June 29, 2010

Tachina


Hogweed umbels attract all manner of insect visitors, including this very striking fly Tachina fera, which has a gruesome life history. It has two flight periods, from May to early June and from July to September.


This tachinid fly lays large numbers of small eggs on vegetation and when they hatch the grubs, alerted by vibrations from an approaching potential host noctuid moth caterpillar, attach themselves to it  and bore into its body, where they develop as internal parasites. There are numerous tachinid fly species, illustrated at the Tachinid Recording Scheme web site.

Life Skills

All along the Northumbrian coast there are eider ducklings learning the rudiments of survival. From the moment they hatch they are completely at home in the sea, bobbing in the surf as buoyant as corks and using those over-sized feet to dive below the waves and explore the seabed.
At this stage they're too small to hunt larger shore crabs that are adults' favourite food items, so explore every nook and cranny for something edible that.....


..... might be dislodged by the incoming tide, all under the watchful gaze ....


... of an anxious adult. Once chuckling alarm call from her and they all head for the comparative safety of the sea....

Photographed at Craster on the Northumberland coast, at the weekend.

Monday, June 28, 2010

Another Weird Wasp

Hogweed umbels are a hive of activity at this time of year, with a constant procession of insects arriving on the flat plates of flowers to either feed on pollen and necter, mate or hunt other insects. This visitor is a male slender-bodied digger wasp Crabro cribrarius which, as far as I could tell, was after plant food rather than animal prey. The female, on the other hand, is a hunter of flies, paralysing them with her sting and then incarcerating them in chambers at the end of an 8 centimetre-long tunnel that she digs in sandy soil. Take a close look at the insect in the picture and you'll notice something odd about its front legs, where one leg segment is broadened out into a flat plate. It looks like it's wearing boxing gloves.

There's a picture of a female here.


Johann Fabricius, the 18th. century entomologist who named this species, gave it the epithet cribrarius -a word meaning sieve - on account of the pattern of pale markings on the foreleg plate that makes it look like a sieve (or more like a collander, if you spend a lot of time in the kitchen). As far as I know, no one has every adequately explained what that odd-shaped leg is for. Not for digging or hunting - the female, which lacks this feature, does that. The suspicion is that males have them as an aid to gripping their mates during mating.

Crabro cribrarius is only about a centimetre long, so is easily overlooked. This one was photographed on the cliff path between Craster and Howick, on the Northumberland coast, last Saturday.

Sunday, June 27, 2010

Gull-with-its-head-on-upside-down

I really can't explain what has happened here. The photo is as taken - no Photoshop trickey - see more of original image below. I can only imagine that this bird has completed a 180 degree roll just before I pressed the shutter release and its head hasn't caught up with its body. If so, I'm amazed at the torsional flexibility of its neck. Taken on the beach at Warkworth today.

Friday, June 25, 2010

Chicken-of-the-woods

This magnificent and still-expanding chicken-of-the-woods Laetiporus sulphureus is growing in a dead oak tree alongside Durham University Botanic Garden's woodland nature trail. So far it has only produced two tiers but there may well be more by the time it reaches maturity, with the largest up to 40cm. in diameter. The underside of each bracket is covered in countless tiny pores which will soon begin to shed spores. 
In this more conventional eye-level view you can see the yellow liquid that often exudes from this fungus. According to M.C. Cooke's British Fungi, published in 1884, and which I picked up in an antiquarian bookshop a while ago, 'as this fungus dries it becomes covered in beautiful crystals of oxalate of potash'. More interestingly, Cooke mentions that 'during decomposition this plant emits a bright phosphorescent light...' Now that is something I really must see: as darkness falls, spooky glowing lights in the woodland. The fungus will probably take two or three months to reach maturity and begin to decompose, just as autumn arrives.

Tuesday, June 22, 2010

Ruby-tail wasp

In my last post I outlined the gruesome breeding habits of the spiny mason wasp, that provisions its nest with paralysed weevil grubs for its larvae to feed on at a later date. In the spirit of Jonathan swift's famous observation, that....

 naturalists observe, a flea

Has smaller fleas that on him prey;

And these have smaller still to bite ’em;

And so proceed ad infinitum.

... here is the mason wasp's nemesis, the magnificently be-jewelled ruby-tail wasp Chrysis viridula. I watched this deadly little parasitoid's behaviour while I was photographing the mason wasp's nest, at the base of the cliffs at Hawthorn Hive on the Durham coast.
There are many species of ruby-tail wasp, also known as cuckoo wasps, each a parasite of a particular species of host wasp, and one thing that they have in common is relentless, restless activity, constantly using their downward-curving antennae to pick up a scent trail in the soil. Ruby-tail wasps have a thickly armoured, iridescent exoskeleton that's impervious to the stings of an angry victim. This species is less than a centimetre long and its colours are more exquisite than anything a jeweller could create.
Once it finds its host's nest hole it uses its antennae to explore the entrance, presumably testing for the specific scent that identifies its prey. Recent research suggests that ruby-tails can produce compounds in their exoskeleton that mimic the scent of their host and so avoid detection and counter-attack.
Next the ruby-tail crawls head-first into the nest hole, to make sure there's no one home, then ....
....... it climbs out and reverses in ....
... until only its metallic green head is visible in the entrance. Inside, it lays eggs that will hatch and produce larvae that will eat its host's young and their weevil grub food store. The hapless host , returning to seal its nest, will never know that the ruby-tail has visited and that its young are doomed.

Monday, June 21, 2010

Buried Alive

This (I'm pretty sure) is a spiny mason wasp Odynerus spinipes , which I found amongst the bloody crane'sbill flowers at Hawthorn Hive last weekend. Notice the distinctive antennae, curled into a spiral at the tip.

And this is its nest hole. The sandy soil that collects on rock ledges at the bottom of the cliffs at Hawthorn Hive offers a perfect, sheltered breeding site. Mason wasps dig a tunnel and lay their eggs in underground chambers, which they provision with paralysed weevil larvae - a living larder for their grubs to feed on when they hatch. The wasp build a cowl-shaped tube over the entrance to the nest hole, seen here in the early stages of construction, but once the nest hole is provisioned and sealed the cowl crumbles away. Its breeding methods may be gruesome, but before that nest hole is sealed it's often visited by another wasp with equally horrifying habits and a truely stunning colour scheme.............

............to be continued.

Sunday, June 20, 2010

Essence of Summer


June is the month for wild roses - and none is more fragrant that the burnet rose Rosa pimpinellifolia. It's the first wild rose to flower, beginning in late May, and produces deep purple rose hips that ripen almost to black. Burnet rose is also incredibly spiney, with a mixture of large prickles and smaller bristlly spines that lodge in your flesh, as I discovered today when I tried to restrict the growth of a plant in my garden.


Burnet rose flowers are normally creamy-white but a few years ago I took a small cutting from a plant growing on sand dunes on the Northumbrian coast which has petals with attractive magenta flecks. It has since flourished in our dry garden soil and the fragrance is fabulous, but it has sent out long runners under paths that have sprouted an ever-widening forest of prickly shoots. Left unchecked, it would probably take over half of the garden but removing it is a painful process, even with gardening gloves..

Burnet rose is first and foremost a coastal species in Durham, although there are some inland populations. This one was photographed on the cliffs at Dawdon in County Durham last week. In Northumberland many of the plants growing in the coastal dunes are much shorter. It's a plant I always associate with summer trips to the seaside, and judging by its invasive tendencies in my garden it's best left in its native habitat.

Saturday, June 19, 2010

Toadpoles

Most of the toadpoles in our local pond have begun to produce legs now and will be leaving the water within a couple of weeks. In this water flea's-eye-view you can see the nostrils fully formed, as the tadpole switches from gills to air-breathing.

Hundreds of toadpoles are congregating in the shallow, warm water around the edge of the pond, where...
... they surface to gulp air with increasing frequency.
Some parts of the pond are beginning to resemble toadpole soup. Only a tiny proportion will survive to adulthood and make it back to the pond to breed in future years.

Friday, June 18, 2010

... damsels in distress

We had a mass emergence of damselflies in our local pond last week, which provided a sudden source of food for some enterprising spiders ...... and provided me with an education in the complexities of damselfly identification, courtesy of Klass-Douwe Dijkstra's Field Guide to the Dragonflies and Britain and Europe.
This, apparently, is a bog-standard mature male common bluetail, but this....
... with its pink thorax, is a 'C' type immature female
Almost as soon as they emerged they began courting, with mature females mating with males in the remarkable 'wheel' configuration. These, above and below, are (I think) common blues in flagrante


After mating some females had already begun to lay eggs on waterweeds, with the male still attached...
This floating reed mace stem was evidently a prime landing pad for oviposting females, with no less than five pairs jostling for space.

Thursday, June 17, 2010

Hidden Defences?


Back in May I posted some pictures of the very egg that this orange tip caterpillar hatched from and since then, with its hedge garlic plant growing in a pot, I've been able to follow the progress of the caterpillar as it has muched its way through the seed pods. Now it's about two weeks old and growing fast. Its colour scheme provides natural camuflage when it aligns itself with the seed pods, but when I enlarged this photo I discovered something else that might be some kind of defence against predators. If you double click this image to enlarge the picture you should be able to see that almost every hair on the body has a small drop of liquid on its tip. This must have been secreted, because we've had blazing sunshine all day and this was taken in late afternoon - the water droplets didn't come from rain or dew. I wonder if the caterpillar secretes some obnoxious substance from those hairs, to keep parasites or predators at bay?  

Wednesday, June 16, 2010

Alien Alert! Be Afraid,Be Very Afraid....


A group of enthusiastic students carrying out a BioBlitz in Durham at the weekend found this remarkable animal. It's a New Zealand flatworm Arthurdendyus triangulatus, introduced into the UK in 1963 and now well established in Northern Ireland and Edinburgh - and also in Durham, where it was first found about 15 years ago. This species is a predator of earthworms and initially had a major impact on earthworm populations in areas where it became established, although recently these depleted earthworm populations seem to have recovered somewhat. It belongs to an animal phylum called the Platyhelminthes, that also includes a number of gruesome parasites, but this predator has a particularly horrific method of dealing with its prey. If you are of a sensitive disposition, you might wish to cease reading now....

The head-end of the N.Z. flatworm is the narrow tapered bit and they can change shape, making themselves very long and thin if necessary. This specimen, which I have on my desk in a securely sealed container as I write, currently looks much as it does in the photos here - coiled up and about 4cms. across, but occasionally it glides around the container and extends its length to about 15cm. This specimen was enclosed in a plastic screw top jar, tightly closed, but managed to escape by sliding along the screw-thread, between cap and jar. They have also been known to explore sewage systems and appear in toilet bowls, leading at least one unfortunate person to believe that they were afflicted with a horrendous intestinal parasite. When they encounter an earthworm N.Z. flatworms wrap themslves around it and them secrete powerful digestive enzymes that effectively reduce their prey to soup, which they ingest. When an earthworm is touched by one of these flatworms it - not surprisingly - reacts violently, as though it had been stung, thanks to the powerful enzymic secretions of the predator - which is why, if you find one, it's not a good idea to handle it with bare hands. They are most often found in cool, permanently moist spots under logs and stones; I know one old churchyard where it seems to like living under fallen gravestones. It seems likely that this alien predator was first introduced by the horticulture trade with plants imported from New Zealand. The wholesale- retail-gardener chain has since provided it with a perfect distribution network. If you find one, your first port of call should be the New Zealand Flatworm web page, where you can find expert advice on what to do next.....

Tuesday, June 15, 2010

Butterfly Hot-Spot

A visit to Hawthorn Hive on the Durham coast at the weekend coincided with the recent emergence of several butterfly species, including this pristine male common blue and .....
.... and its rather more muted female consort.
The raised beach at Hawthorn Hive - a legacy of past colliery waste dumping - is covered with large patches of bird's foot trefoil, food for common blue and dingy skipper caterpillars, so this sheltered bay is a great spot to find both species - and also several others. The cliffs provide shelter from the wind, unless it's blowing from the East - and the prevailing wind is mostly south-westerley. Paradoxically, it's only the raised beach - produced by past industral activity - that protects this wonderful site for flowers and insects from being inundated by the waves. It's slowly being eroded and once it has gone the waves will be able to reach the base of the cliffs where.....

..... this green-veined whire was collecting nectar from bloody crane'sbill flowers...

...... while this large skipper basked on the same plant's foliage....
... and another .... amongst the grasses.
On the cliff tops above small heaths were flying in the grassland. They have a very distinctive way of sunbathing. Most butterflies orientate themselves with their back to the sun and open their wings to absorb the heat - like the common blues and large skipper above. Small heaths keep their wings folded but turn their whole body at 90 degrees to the sun's rays, so the underside of the wings on one side of the body only faces the sun.