Wednesday, June 30, 2010
Tuesday, June 29, 2010
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.
Monday, June 28, 2010
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.
Sunday, June 27, 2010
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
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.
Tuesday, June 22, 2010
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.
Monday, June 21, 2010
Sunday, June 20, 2010
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.
Friday, June 18, 2010
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
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
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
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 .....