Bumblebee mites

Today's Guardian Country Diary is about this queen bumblebee Bombus pratorum that's infested with mites.

The mites belong to the genus Parasitellus and this individual is particularly heavily infested, but her plight isn't as dire as it might seem. These mites don't feed on the bee or transmit disease in the way that Varroa mites of honeybees do. They're commensals, living in the bees' nests and eating the sticky coating from pollen grains, as well as consuming debris that accumulates in the nest. Other than using some of the pollen that the bee collects, they don't seem to do any serious harm and may indeed be beneficial.

It's usually newly-emerged queens that are as heavily infested as this and it does sometimes seem that they are struggling under the load of hitch-hikers, but after a bit of a rest this one took to the air again without much difficulty. The mites tend to congregate in parts of the bee where it's difficult for their host to comb them off with its legs.

The mites spread between bumblebee nests via flowers. When as infested bee visits a flower a few hitch-hikers dismount and hide in the blossom until another pollinating bee arrives, then they climb on board and are carried back to its nest.

Lowlife

A couple of months ago I stacked some old broken fence panels on the soil at the bottom of the garden and when I moved them today I found they were sheltering all sorts of interesting soil invertebrates.Two species are illustrated below.

This wonderfully articulated centipede was living in the soil under the wood. Judging by the number of pairs of legs, I think it must be Haplophilus subterraneus, which has between 77 and 83 pairs. The books say that it sometimes glows in the dark if it's disturbed at night, so I might go back and have another look later tonight.

These are springtails - possibly Folsomia candida. There were thousands of them, probably eating fungi that were growing on the decaying wood panels. 

Springtails are noted for their ability to hurl themselves into the air using a spring-loaded appendage called a furcula under their tail. If you've never seen a springtail jump, take a look at this clip from David Attenborough's Life in the Undergrowth


For some more, higher magnification images of springtails, click here

For some detailed information on the Collembola - the subclass of six-legged invertebrates to which springtails belong, click here

Take a look at Steve Hopkin's wonderful web site for ID photos of springtail species and for some truly stunning pictures of these tiny animals take a look at this Flickr gallery belonging to Eddie the Bug Man (Eddie Nurcombe)

The Snail, the Woodlouse and the Millipede with disgusting but valuable habits...

If this post title sounds like a modern-day Aesop's fable well, in a way it is, because it does have a moral. Not one, but two morals...

Have you ever wondered what millipedes eat? Probably not, but if you have the books will tell you that they are herbivores that sometimes eat gardeners' seedlings and are therefore a pest.

When I found this millipede clinging to the back of a garden snail's shell I wondered what it was up to. Could it be that millipedes attack snails? If so, they'd go up in my estimation.

All was revealed when the snail glided away, almost running over a woodlouse in the process but leaving some tell-tail evidence: snail poo.

Yes, remember you read it here first: millipedes eat snail poo. 

Maybe not the most pleasant addition to the sum total of human knowledge, but there is a moral to the story. 

Millipedes do indeed eat some of the gardener's seedlings but they are also part of a vast community of soil invertebrates that play a role in cycling of minerals. This snail poo might well be all that's left of some lettuce seedlings I planted out a few days ago, but at least I'm secure in the knowledge that, once they've passed through a millipede's digestive system, some of the nutrients will find their way back to the soil and feed the next batch of my seedlings that a snail snacks on....

The second moral is that the only sane way to approach vegetable gardening is to recognise that you are part of the great web of food interactions and nutrient recycling, and to become reconciled to the fact that some of what you plant - sometimes most of what you plant - is going to pass through the digestive system of a snail and maybe a millipede too, rather than your own.

So, I think of gardening as a source of endless photo-opportunities and don't expect to harvest too much. It's the way to reach gardening karma. 

So, on to the next question: if you are a snail, what does it sound like when a millipede walks past? Probably, like this...

Slug slayer

After 12 hours of apocalyptic rain the clouds finally parted and the sun came out - and so did the frogs. Now that they've spawned in the garden pond, which is swarming with tadpoles, our resident frogs spend most of their time lurking in the flower beds and there's nothing they like better than a good rain storm, which brings all the slugs crawling out from the undergrowth. 

Very satisfying for the frogs, and from a gardener's perspective too, when they swallow these slimy pests.



The frogs tend to be very wary when they first emerge from hibernation but as the months go by they become accustomed to me gardening around them and sometimes become quite tame. On several occasions in the past I've managed to entice one to take small slugs presented on the tip of my finger, which makes a change from hand-taming robins with meal worms.

You put your left leg in .....

Bumblebees, like this common carder bee, have a distinctive pattern of behaviour when they are too lethargic to fly. This one was foraging very slowly on dandelions in Teesdale this morning, showing no inclination to fly, but when I gave the flower a little prod ....


Double-click for a larger image

..... it did this, the bee version of the hokey-cokey (for those to young to known what this dance is, click here!). It raised its middle leg and waved it about. I've noticed that comatose bumblebees often show this kind of defensive behaviour when they are disturbed.

When I passed by again, half an hour later, when the morning had warmed up a little and it had presumably refuelled on dandelion nectar, it had gone.

Gold standard

If I had any sense I'd probably have dug out the dandelions in the gardens long before now because they seed themselves so prolifically, but instead I've been watching the constant stream of bees - with their pollen baskets stuffed full of orange dandelion pollen - visiting the flowers all afternoon. There are golden drifts of dandelion flowers everywhere just now - along road verges, on waste ground and in pastures - and every year they provide a reliable source of vast amounts of pollen and nectar for bees.

The strange thing is, though, that dandelions don't need nectar, pollen or pollinators to produce a full crop of seeds - for the reason why, click here.

Africa Gomez, over at Bugblog, has more pictures of some of dandelions' many insect visitors in spring.

Wildlife on Walls: 10. Brittle Bladder Fern

Brittle bladder fern Cystopteris fragilis is one of the characteristic wall ferns of North East England, growing in crevices in shady limestone walls or in mortar and often thriving in old industrial sites, such as the inner walls of railway bridges and the ruins of old lead mine workings in the Durham dales.

It owes its common name to the shape of the coverings over the clusters of spores on the underside of its fronds and to the brittleness of the frond stems, which are succulent and snap easily.

Click here for more plants and animals that live on walls

Elegant moss capsules

These elegant spore capsules belong to the common woodland moss called swan's neck thyme moss Mnium hornum and their presence is testament to the fact that the individual plants that bear them are female. Sometime back in the winter the egg cell inside a microscopically small flask-shaped structure called an archegonium, tucked away somewhere down amongst the leaves,  was fertilised by a swimming male cell called an antherozoid, that swam across the surface film of water on the moss plants, attracted by organic acids secreted from the neck of the archegonium. Countless similar sexual encounters between moss plants occur every day on the woodland floor on mild, wet days in winter and early spring.

And these are the structures that release the male sex cells. The glistening structures packed amongst the rosette of leaves on the shoot tips of these male plants are the antheridia - flasks full of male antherozoids, each equipped with a whip-like flagellum that propels it through the film of water. Sometimes rain-splash in the rosette of leaves will hurl water droplets laden with antherozoids towards surrounding female plants. Sometimes small soil animals may carry antherozoids on their bodies.  The odds against a successful fertilisation are long but the antherozoids are many and the net result is a fertilised egg cell, and ultimately a spore capsule full of spores that will be dispersed on the wind and grow into a new moss plant. Mosses have been reproducing like this for over half a billion years, surviving five great mass extinction events that have extinguished many other forms of life. 

Durable little plants, aren't they?

Tawny mining bee

This is a sight to gladden the heart if, like me, you grow soft fruit: a tawny mining bee Andrena armata. They've been breeding in our garden for many years, laying their eggs in tunnels that they mine in bare soil under the hedge. They are remarkably industrious pollinators of early-flowering red currents (seen here), black currents and gooseberries - and very attractive little bees too, with that tawny fur. This species seems to be near the northern limit of its UK distribution here in Durham, except for an outlying population in Scotland.

The Bees,Wasps and Ants Recording Society has a very useful information sheet on this species which you can download by clicking here.

Newly minted butterfly.....

We found this newly-emerged green-veined white, still 'pumping up' its hind wings, when we walked along the sea cliffs south of Seaham this morning.

This early purple orchid - the first I've seen this year - was flowering in the meadows near Hawthorn Dene and was already past its best. Spring flowers are enjoying a very short season this year, having been held back for so long............... 

........... but the display of cowslips in the same meadow is magnificent. We also saw ....

............ a few false oxlips, which are the natural hybrid between primroses and cowslips.

Down on Blast beach, at the base of the cliffs, landslips have created sheltered, steep banks at the top of the beach that are carpeted in primroses.




The finest floral display, though, is at the top of the cliffs, where the gorse is in full bloom, with its wonderful coconut aroma and .....




...flowers that are so closely packed together that they completely hide the bushes