New Year Plant Hunt in and around Durham city today

A second day of New Year Plant Hunting, this time along the banks of the river Wear and along woodland edges and hedges. Nineteen species in flower this time, of which these are some of the most pleasing:

Alder catkins

Hazel catkins

Hogweed

Nipplewort Lapsana communis

Lesser celandine, flower petals eaten by a slug but very attractive variegated foliage.

...... and cowslip, flowering four months early.

The cowslip was on the Durham University estate, on the Mountjoy site, about 400 metres from an area that was seeded with wild cowslips about 20 years ago. Since then they save seeded themselves on various places, most likely with seed carried on feet of staff and students. This single flowering plant was amongst a population of over 50 non-bloomers, all with very vigorous new leaf growth, on a very sheltered grassy bank under an alder.

The ladybird and the ant ....

We found this tiny 22-spot ladybird on a dead hogweed stem in Teesdale a couple of days ago. Teesdale is close to the northern limit of its recorded distribution in England.

According to the UK Ladybird Survey web site this species has a particular liking for hogweed and feeds on mildews. A research paper published in 2011, which you can read here, revealed that these mildew-eating ladybirds are attracted to volatile compounds that are produced by mildew.

What's less certain is why this ant seemed to be engrossed in the hogweed stem. Maybe it too was feeding on the mildew too, or perhaps it had chewed that long trench in the stem tissue ...........

It looks like it's chewing all the soft, rotting tissue from the outer stem of the hogweed.

Whatever the reason, it was very reluctant to move and when I finally disturbed it the ant just crawled into the hogweed umbel and them resumed chewing the plant surface.

Shiver Stabilisation System

I was so cold  and shivering so much when we walked along the river Wear near Durham this afternoon that I could hardly hold the camera still....... which made these pictures a severe test of Panasonic's image stabilisation system. Even dead hogweed umbels are attractive when they're covered in a rime of frost.

I takes more than sub-zero temperatures to stop gorse flowering.

The Year of the Slug?

I hadn't really realised what an amazing summer this must be if you happen to be a slug, until we went out for a walk after heavy rain a couple of days ago. The footpath was covered with these slimy molluscs, but so too were the flower umbels of hogweed. Wet weather seems to encourage slugs to climb tall flower stems to feed on petals and pollen. Why do they bother, when there is so much food at ground level?

This rather colourful local variety of Arion ater, with an orange skirt, had climbed a dandelion stem to feed on the florets.

Meanwhile, the same rain storms have done serious damage to pollinating bees. This bumblebee was so saturated by rain that it was diffcult to decide what species it might be.

Architecture in the Snow

A snowfall has a wonderful tendency to turn pieces of natural architecture into something magical....

... and to sprinkle a bit of magic over man-made architecture.

Hogweed stems

Durham Cathedral from Observatory Hill

Lunchtime today

Mull of Galloway 3: An Unlikely Defence against Rabies

Last week we spent a few days in Galloway where, down on the Mull of Galloway we found several of these stunning rose chafer beetles Cetonia aurata. They seem to have a particular liking for hogweed flower umbels - in fact, I don't think we saw any on any other flower.

I spent an hour on a hot afternoon photographing them and - for such large beetles (20mm. long) - they are remarkable active, taking to the air with a loud buzz if you get too close. When rose chafers fly they extend their wings and then close their wing cases (elytra) over their abdomen again, unlike beetles like the ladybird that keep their wing cases extended to generate aerodynamic like. You can see a wonderful compostite picture of a rose chafer in flight at http://en.wikipedia.org/wiki/File:Cetonia_aurata_take_off_composition_05172009.jpg

- take a look, you'll be amazed.

Also take a look at a video of this beetle feeding and taking off at http://www.arkive.org/rose-chafer/cetonia-aurata/video-00.html

and another of one hatching from a pupa at
http://www.youtube.com/watch?v=vDH2UV41OLA

While I was searching for these videos on the web - which has a fantastic tendency to throw up random, interesting items - I came across this remarkable snippet of information from a 150 year-old edition of the British Medical Journal (the 'hydrophobia' it refers to is the old name for rabies):

ALLEGED REMEDY FOR HYDROPHOBIA. At a recent meeting of the Academy of Sciences in Palis, M. Guerin-Meneville sent in a letter on the Cetonia aurata, or rose beetle, which for some time past has engrossed the attention of naturalists as a remedy for hydrophobia. M. Meneville stated, from personal experience, that in the governments of Voroneje and Koursk, in Russia, it is customary to give dogs half a beetle in powder from time to time, mixed with bread crumbs, as a preservative against that disease;

British Medical Journal 5th. December 1857,Medical News p. 1017

Source: http://www.bmj.com/cgi/issue_pdf/admin_pdf/s4-1/49.pdf

Daggers Drawn

This ungainly looking fly with a long, straight proboscis is Empis tessellata, seen here feeding on hogweed nectar. That isn't its only reason for lurking on hogweed umbels though - it's a predator of other small flies that are attracted to the flowers.

Individual hogweed flowers secrete nectar from the surface of the ovary, from which a pair of styles with stigmas at their tips arise. The nectar is a very convenient energy source for small insects. By providing small amounts of nectar on numerous flowers, the plant ensures that the pollinator must wander all over the surface of the umbel to collect it, accidentally pollinating stigmas of many flowers in the process.

Empidid flies are sometimes known as dagger flies, on account of those long piercing mouthparts. This is the largest British species.

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.

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.

Aromatic Umbellifers

Hogweed Heracleum sphondyliumSweet cicely Myrrhis odorata

The carrot family (Umbelliferae) includes several species with seeds that contain aromatic compounds that are used as flavourings – cumin, fennel , celery and caraway are notable examples. The bottom picture here shows the ripe seeds of sweet cicely Myrrhis odorata, an umbellifer which was once cultivated for its aniseed flavour and used to sweeten puddings, in the days before sugar was a cheap, easily available commodity. The species is widely naturalised in North East England and every part of the plant has an aniseed aroma. Apparently, the seeds were also once used to make a pleasantly aromatic floor polish. The top photo is of hogweed Heracleum sphondylium seeds, which are not edible but do contain a fruity, aromatic oil that has a very refreshing scent – try crushing some ripe seeds between finger and thumb and you’ll see what I mean. The oil is concentrated in those four dark brown stripes, which are oil glands.

An Alternative Point of View

One of the advantages of compact pocket digital cameras is that they offer amazing depth of field in images. Another is that they make it easy to take pictures from unfamiliar angles – from ground level, for example. Put the two together and you get a different perspective on the natural world, that’s more familiar to a ground feeding bird or small mammal that spends it’s time looking upwards, rather than to we humans who inevitably see much of the living world from a lofty perspective. From the top: germander speedwell, foxglove, hogweed and spotted orchid.