Wednesday, June 28, 2017

Scarlet lily beetle

This year, for the first time, scarlet lily beetles Lilioceris lilii appeared in my garden. There were only two, which turned out to be a male and a female, and they came with some lily bulbs imported from Holland that I bought in a supermarket.

Being curious, I kept them under observation in a jam jar and soon discovered why these lovely insects are considered to be such notorious pests.

They mated overnight and by the next day had begum to lay rows of their round-ended, cylindrical eggs on the lily leaves that I supplied to them.

The adult beetles are formidable eaters, quickly nibbling holes in the edges of leaves that I gave them to feed on, but the grubs, when they hatched a few days later, were in a different league altogether.

They quickly began chewing holes in leaves and half a dozen of them could demolish a lily leaf in less than a couple of hours.

But, most remarkably, they did this while covering themselves in their own frass, which camouflaged them as bird droppings. This one has only just begun to anoint itself but they quickly became completely hidden in a mound of their own droppings.

From a gardener's perspective, these are extremely destructive insects and I can quite see why, in the worst affected parts of the country, gardeners have had to give up growing lilies. 

These gaudy insects have spread from their native Eurasia throughout most of the temperate northern hemisphere.  They first appeared in England in a Surrey garden in 1939 and by 1943 had reached the United States. Their spread northwards in England, and now into Scotland, has been rapid in the last decade, no doubt helped by a wholesale and retail distribution system for lily bulb sales that has ensured that they can reach every part of the United Kingdom.

I never once saw them attempt to fly. If you disturb the adults they just fall off the plant and pretend to be dead until the danger has passed.

The Royal Horticultural Society has a very good web page devoted to these insects and is also conductiing a survey of their spread, although I have to say the words 'horse', 'bolted' and 'stable door' come to mind!

These two individuals were the only ones that appeared in the garden and my lilies are doing fine, almost flowering in fact, but I wonder whether I'll be so lucky in future years

Tuesday, June 27, 2017

Monkey flowers: summer opportunists when river water levels fall

In summer, when the water level in the upper reaches of the river Wear drops, its gravelly banks are colonised by a natural rock garden of plants. This year, after a long dry spell, its flora is looking particularly attractive. Many of the plants are garden escapes, most likely from garden refuse swept down the river from upstream. 

The most eye-catching are monkey flowers, whose creeping stems become woven into the coarse gravel and resist the flow of the current when the river rises again. The most beautiful is the coppery monkey flower Mimulus x burnetii, a sterile hybrid between Mimulus guttatus and M. cupreus, both from western North America.

It isn't very common because it does not produce seeds and only spreads from vegetative fragments, but wherever it does appear its warm coppery tones make it very conspicuous. 

This is one of the parents, monkey flower Mimulus guttatus, which does set seeds and is a colourful feature of the river gravels all along the upper reaches of the river Wear.

Both plants are very easy to propagate - just a short length of the creeping stem with a leaf node will produce new roots and shoots very quickly.

Sunday, June 25, 2017

Orchids on the Durham coast

Durham's magnesian limestone grassland is famous for its orchids. Yesterday, when we were walking along the coast near Hawthorn Dene there was a sensational display, in the hay meadow at the mouth of the dene itself and even more so in the thin soils around the old quarry. 

There were many hundreds of spotted orchids and scores of pyramidal and fragrant orchids. There were also plenty of twayblades, but it's hard to estimate their numbers because their green colour makes them easy to overlook. 

I think this was the best orchid display that I can remember here.

Fragrant orchid

Pyramidal orchid

An albino common spotted orchid

Common spotted orchid

Twayblade orchid

This is the area around the quarry with the highest density of orchids, growing in a thin veneer of soil over limestone. Other species in flower here included centaury and yellow-wort, greater knapweed and carpets of bird's-foot trefoil.

Friday, June 23, 2017


Throughout June many of the plants in the garden have been decorated with 'cuckoo spit', the frothy bubbles blown by froghopper nymphs feeding on the sap.

Outside of their bubble bath, the nymphs are cute little insects .....

.......with lethargic movements, strange, two-toed feet........

.... and a bulbous nose, which acts as a pump when they suck sap through a stylet that punctures the plant.

Now the nymphs are beginning to turn into adults and they are incredibly energetic, leaping through the undergrowth with tremendous speed at the slightest touch.

An adult froghopper can catapult itself to a height of 140 times its body length. That’s equivalent to a human jumping over a bar set at 260 metres, when the current Olympic record stands at 2.39 metres.

In 2003 Cambridge neurobiologist Malcolm Burrows, analysing a theoretical  high jump contest between fleas and froghoppers, found that the latter coming out on top. Eleven percent of a froghopper’s body mass is concentrated in two jumping muscles but these can’t contract fast enough to generate the insect’s take- off acceleration of four metres per second in the first millisecond of its jump. That’s achieved with a leg-locking mechanism which, when it breaks free, releases a force of over 400 times the body weight of the jumper, over 130 times greater than human’s legs can manage.  The key to this performance is resilin, the most efficient elastic protein known,  which stores energy accumulated by the insect’s contracting muscles and releases it with explosive force, generating acceleration of about 400g; we humans black out under a force of 5g. 

The adults of Philaenus spumarius display a range of colour patterns. Many are just plain brown but this individual sported a smart two-tone colour scheme.

Monday, June 19, 2017

Orange tip caterpillar food plants

We have all three of the commonest food plants for orange tip butterflies in the garden - hedge garlic (Alliaria petiolata), lady's smock (Cardamine pratensis) and sweet rocket (Hesperis matrionalis), though I only encourage the last two because hedge garlic is so invasive.

This year, for the first time, I've noticed the caterpillars feeding on the developing fruits of this plant, honesty Lunaria annua.

I think they probably find it tougher to chew than the other three plants but they seem to be growing rapidly on this diet.

The only drawback, from the caterpillar's point of view, may be that they are more conspicuous on these disk-shaped fruits. When they align with the long, thin pods of the other three plants they are quite hard to spot because their countershading colour scheme works very well in those circumstances and they don't cast a bold shadow..

Saturday, June 10, 2017

Barn owls

It used to be the case that you could go for years in my part of Durham without seeing nesting barn owls. This week I've had the pleasure of watching two pairs.

The first was a bird hunting over open rough grassland, with scattered hawthorns, beside an old railway line that is now a public bridleway.

Barn owls almost seem to float across the ground, then suddenly perform a wing-over and stoop on their prey. This one struck three times before it rose with something small and furry in its talons, flew high over the trees and headed towards some old farm buildings where it must be nesting.

The sighting of the second pair was very close to home, nesting in a hollow ash tree on a farm belonging to a friend. She has farmed there for over forty years but this was the first barn owl that had ever graced them with a nest, so she was absolutely delighted. 

I spent yesterday evening watching a parent bird flying to and from the nest, hunting over the pastures amongst the cattle at sunset. Sometimes it flew right through the orchard where I was standing, no more than twenty metres away.

A magical evening, watching a truly stunning bird.

Friday, June 9, 2017

Springtails walking on water

Springtails are probably the most numerous animals in our garden composting bins. Every time I lift the lids I can see hundreds jumping around on the surface of the decaying kitchen waste and rotting garden weeds.

Recently, after heavy rain, I saw them in a new context. A container beside one bin had filled with rainwater and I noticed little pale grey patches floating on the surface.

A close look revealed that they were springtails. 

Individually these tiny animals are rather cute, so light that they barely dimple the water surface. 

Collectively, there were hundreds of them floating in huddled groups on the meniscus.

The springtails could easily escape the surface tension, using the little device in their tail called a furcula, that acts rather like a pole vaulter's pole when it's straightened, catapulting the animal into the air.

In this picture you can also see a tiny brown tick floating amongst the springtails.

How they all came to be on the water surface is a mystery.

There are more pictures of springtails here 

Wednesday, June 7, 2017

Weardale in early summer: St. John's Chapel

Weardale is at its most beautiful in June.  These are a few photographs taken recently around the village of St. John's Chapel, in the middle of the dale.

Burnet rose, the most fragrant of all the native wild roses.

A single wood cranesbill plant in a sea of buttercups.

Meadows full of buttercups, seen from Chapel fell

A froth of cow parsley flowers along roadsides and around the edge of fields.

Hawthorn in bloom along the footpath beside the river Wear

Hawthorn still blooming beside Harthope burn. Water levels are low after a very dry spring.

Glorious hay meadows

Lady's mantle and wood cranesbill

Meadow foxtail grass in flower

Pignut's lacy umbels

Lambs fattening

Wood cranesbill