Is the Only Good Slug a Dead Slug?

Even the most ecologically-orientated gardeners sometimes harbour murderous intentions towards slugs. When they devastate our crops we might spurn slug pellets in favour of beer traps, parasitic nematode worms that eat them alive or simply crushing them under foot - but do all slug species in gardens deserve to die? Occasionally I read claims that there are good slugs and bad slugs, and it’s certainly the case that the smaller, most numerous species do the most damage to vulnerable garden plants. The Little book of Slugs , published by the Centre for Alternative Technology, nominates the field slug (Deroceras reticulatum), the keeled slug (Milax budapestensis), the garden slug (Arion hortensis) and the black slug (Arion ater) as the worst offenders but from time to time I read claims that some species are harmless to garden plants. How true these claims are is open to question - so much of what’s printed in wildlife gardening books seems to be simply copied uncritically from older sources that may well have been wrong – but next spring I plan to do some tests of my own to see if there is any slug species that can be trusted to spend the night in a plot of young, succulent lettuce plants. The most likely ‘good slug’ seems to be the great grey or leopard slug Limax maximus – like this one (above) that’s spending winter under loose bark on an old log in my garden. Edward Step FLS, in his book Shell Life: An Introduction to the British Mollusca, published in the early years of the 20th. century, ventured the opinion that this species “declines all foods containing chlorophyll” but was particularly partial to “kitchen garbage that is not green, such as fat, bread, meat scraps and milk”. More gruesomely, he found that this species was a cannibal, eating the remains of fellow slugs that he’d killed after finding them in milk jugs in his kitchen. Whatever the great grey’s taste in food, it certainly has some very exotic mating habits which you can watch at

http://www.youtube.com/watch?v=GSW9kWIRCOQ

Harlequin II: the nightmare continues.......

It turns out that the harlequin ladybird (widely tipped to devastate our native ladybird population) that I reported in my last post has accomplices. Nyctalus (from http://standandstare-nyctalus.blogspot.com/) and I found more in the same place today, including this multispotted morph of this highly variable species, and – much more interestingly – a fully developed larva that had anchored itself to an ivy leaf by its tail and was about to pupate. Presumable it will overwinter as a pupa and hatch as an adult next spring, but the fact that the species is breeding so late in the season up here in the North is quite remarkable. I wonder, incidentally, whether this species is attracted to ivy, given this plant’s attraction for other insects in autumn, which would be easy prey for a lurking harlequin ladybird while they are preoccupied with nectar and pollen.....

Harlequin ladybird

Had my first sighting of what I believe was a harlequin ladybird Harmonia axyridis yesterday, when I found it feeding on ivy flowers near the entrance to Durham University Botanic Garden. It matches the published descriptions and photographs, although the legs are usually (but not always) brown, whereas in this specimen they are almost black. It has already been recorded in Durham and further North (see http://www.harlequin-survey.org/images/maps/harlequin_years_20July09.jpg) but this is the first that I’ve encountered. It seemed to be nibbling away harmlessly at the nectar on the surface of an ivy flower, but maybe it was just lurking and waiting to do something unspeakable to a visiting native ladybird species....... current opinion is that it could have a devastating effect on our insect fauna as it becomes more widespread - see http://www.ceh.ac.uk/news/news_archive/2009_news_item_28.html. I'll certainly be keeping a lookout for it next year. The wing colour patterns on the harlequin ladybird are astonishingly varied (see http://www.harlequin-survey.org/recognition_and_distinction.htm#).

Deer at Dawn

The fog hadn’t long been cleared by the rising sun and a stiff breeze when we can face-to-face with this roe deer as we rounded a bend in a footpath near Wolsingham in Weardale. It’s hard to tell which of us was more surprised but what is certain is that I was a bit slow off the mark, so all I got was this picture of it bounding off, flashing its distinctive alarm signal – the heart-shaped patch of white hairs on its rump. I guess it didn’t smell or hear us approaching, as we were downwind and the sound of wind through the autumn leaves drowned out our footfall.

A little later we encountered this hind and her fawn on the edge of a field and this time we weren’t spotted until we’d had a good look at them grazing in the early morning sun.

This fawn would have been born last spring and will stay with its mother through the winter.

Eventually they picked up our scent, and were gone in an instant

Weeping Widow?

Steve Ansdell, Durham University’s Horticultural Superintendant, showed me this spectacular display of toadstools in the grounds of Josephine Butler College today.

There must have been well over a thousand of them, spread over an area the size of a football pitch. By far the finest display of toadstools I've seen so far this autumn. They fit the description of Weeping Widow Lacrymaria velutina.

The caps of the young specimens had a distinctly fibrous appearance and the microscopic characters fitted the text-book description for this species.

Dark brown gills becoming increasingly black with age and, although it's not too evident in this specimen, wisps of the fibous veil that covered the gills in the young toadstool still clinging around the edge of the cap....

 

....and a distinctive black spore print

For a microscopic exploration of this fungus, take a look at http://beyondthehumaneye.blogspot.com/2009/10/these-are-radiating-gills-of-toadstool.html

Sunbathing Survivors

With the first hard frosts probably no more than a couple of weeks away, insect numbers will soon plummet but for now, during what I believe has officially been declared an ‘Indian Summer’ by the Met Office, there are still quite a few around. This parasitic hymenopteran, which I think is a male Gasteruption jaculator, was feeding on a late-flowering hogweed umbel this afternoon. The crane fly (below) had arranged itself decorously over a yellowing Norway maple leaf, soaking up the weak afternoon sunlight.

Season of Mouldy Fruitfulness

A few days of mild, humid weather has produced some fine displays of moulds and rust fungi on fruits and leaves that are reaching the end of their useful lives. This bramble is afflicted with both diseases – Botrytis mould consuming its rotting fruit and the rust fungus Phragmidium violaceum producing some beautifully colourful effects on its ageing foliage. There’s a peculiar kind of beauty to be found in decay.

Pristine bramble fruits, before Botrytis fungus found them.....

Life's a Beech

This autumn the upper surface of many of the leaves on young beech trees around here are carrying these cylinrical, hairy galls caused by a midge called Hartigiola annulipes that laid its egg in the leaf surface back in the spring. Opening them up reveals the hollow chamber inside with the larva developing down at its base. In a week or two, when it's mature, the gall will separate and fall from the yellowing leaf, shortly to be buried under a carpet of fallen leaves. The larva will pupate there, until the adult midge emerges in spring, at just the right time to lay its eggs in the soft tissue of a newly expanded leaf.

Gall sectioned vertically.....inside, there's a large, hollow chamber

The larva, tucked in here down at the bottom of the gall chamber, still has plenty of room to grow.

Drinking in the Last Chance Saloon

Just when most of our flora finishes flowering, ivy comes into bloom and provides a last-minute autumnal energy top-up for insects like this drone fly (below, feeding on ivy pollen) and red admiral (above, drinking nectar), before the frosts arrive. To appreciate why its flowers are so attractive to insects, you need to take a really close look on a mild humid morning, when the disc at the centre of the flower is absolutely swimming in secreted nectar (see lower two photos) and newly open stamens are still full of fresh yellow pollen. It’s difficult to underestimate the value of this plant as an energy source for insects that hibernate, bearing in mind its wide distribution, the vast number of flowers produced on just a single plant and their long flowering period.

Freshly opened ivy flowers, oozing nectar and laden with pollen.

Honeybee in Disguise

The first time I saw one of these bees with a distinctive band of white hairs along its thorax I spent some time leafing through field guides unsuccessfully trying to name it – until I realised that it was a honeybee that had been feeding on Himalayan balsam flowers (see http://cabinetofcuriosities-greenfingers.blogspot.com/search/label/Himalayan%20balsam). When the bee pushes its way into this flower to reach the nectar the hairs on its thorax pick up white pollen from the stamens that are in the roof of the floral chamber. As it backs out it brushes the stamens away exposing the stigma, ready for the next pollen-laden visitor to the balsam flower to deliver its stripe of pollen to the sticky stigma. I've also seen wasps with tell-tale white thoraxes which have evidently been collecting nectar from the same source. I photographed this ‘striped’ honeybee today on wild carrot, after it had exited the Himalayan balsam flowers nearby.