The unstoppable advance of harlequin ladybirds

 It's now a 14 years since I first saw a harlequin ladybird in Country Durham, and a decade since I first found one in Teesdale. Yesterday, in precisely the same location, there were hundreds, feeding on ivy nectar. This abundant supply of energy in autumn, coupled with their capacity to remain active in cold weather, must surely be important factors in the phenomenal success of this invasive species. 

Harlequin larvae seem to have an affinity with sycamore, perhaps because of the vast supply of sycamore aphids that they find on the leaves. At this location sycamore and ivy grow together, which might account for the population explosion, with dense ivy also providing a sheltered winter hibernation site.

There now seem to be two dominant morphs in this local population, one black with four large, ragged red spots and the other red with multiple black spots, which is more common. 

 This species is known to be a predator of our native ladybirds and can also transmit a parasite that kills other species. It also feeds extensively on eggs of butterflies and moths. Over the last two decades it has spread rapidly, from south east England to the Scottish border. It originated in central Asia but was introduced elsewhere in misconceived biological control programmes aimed at 'environmentally friendly' aphid control in greenhouse crops. Wherever it has been introduced it has escaped and has had a detrimental effect on native insect populations.

Goldfinches and sunflowers on the Durham coast

Earlier this month, the largest flock of goldfinches that I've ever seen congregated on the Durham coast. There must have been well over 200 birds, feeding on seeds of the limestone flora on the cliff top above Blast beach. Most seemed to be eating meadowsweet seeds, but there was also a large store of knapweed and hemp agrimony seeds for them to feed on. Many of the birds hadn't moulted into full adult plumage yet and were quite hard to spot on the ground, but when they all took to the air at once they were a magnificent spectacle.   

Further along the coastal path, near Hawthorn dene, two fields have been sown with a wild bird food crop, including fodder radish, quinoa (below) and sunflowers which will provide food for finches and buntings later in the winter, when the supply of wild flower seeds runs low. Last winter similar crops attracted large flocks of linnets.

Common darter dragonflies laying eggs

A couple of weeks ago I watched these two common darter dragonflies, coupled together in tandem, laying eggs in a shallow pool near Hawthorn dene on the Durham coast. I'll be keeping an eye on it, whenever I pass by, to see how well the nymphs are developing. 

It may be a race against time for them, because these shallow pools on the limestone dry up completely in early summer in years when there is a drought. They dried up for several weeks this year, and last. 

I imagine that their success will depend on how the rest of the aquatic fauna, their food source, develops over the next few months. If frogs or toads lay eggs in the pools in spring, as they sometimes do, then the nymphs will have plenty of tadpole food and might complete their development and hatch as adults in less than a year, which they are capable of, if conditions are good.

While I was watching these two I noticed that they were attacked, unsuccessfully, several times by a much larger southern hawker - the first time I've ever noticed a display of aggression between dragonfly species.

 

Bank vole

I usually only have fleeting glimpses of bank voles, but thanks to a fellow walker along the Deerness Valley Way in County Durham I had a good view of this one. Every day this kind-hearted benefactor leaves small handfuls of food for birds on rocks along this former railway line. Today the bank vole found the free handout irresistible, even though there's an abundance of autumnal natural food all around. This tiny mammal needs to be careful though - kestrels and barn owls also hunt along here.

 

Stubble field annual wild flowers

 Some common annual wild flowers that flourish along field margins, in the few weeks between a cereal crop harvest and the arrival of the plough.

Common poppy, rejuvenated by warm sunshine, after the very wet weather during this summer's harvest in Teesdale

The tiny, pale blue flowers of field forget-me-not. Many  arable weeds have small flowers but are well worth a closer look.

Scarlet pimpernel has a long flowering period that often extends until the end of October. The flowers always close in mid-afternoon, unless rain clouds cover the sun, when they close quickly to protect their pollen -  behaviour that has earned the plant the reputation as 'the poor man's weather glass'.

Field pansy, a tiny but beautiful flower that has contributed to the parentage of garden pansy

Sky-blue flowers of common field speedwell, a native of the Caucasus that was first recorded in the wild in England in 1826 and has since spread throughout Britain. Like many arable weeds, its seeds are transported far and wide in mud on shoes, hooves and agricultural vehicle wheels. 

Common cudweed, with silvery leaves and tiny yellow flowers.

Common sowthistle whose light seeds, supported by a parachute of hairs, are carried long distances on the breeze

Himalayan balsam nectar

 Himalayan balsam is notoriously invasive and the chances of ever eliminating it on a large scale seem negligible. Even when plants are pulled up there is always a large seed bank in the soil, and flooding carries the seeds far and wide along river valleys. But it does have at least one virtue: it's a very rich source of nectar late in the year, when few native nectar-rich plants are available. Bees and wasps find it irresistible.  

The flowers have a distinctive pollination mechanism, with anthers positioned in the roof of the flower, so they deposit pollen very efficiently on the upper thorax of visiting insects, like the honeybee above and the wasp below.

Persistent insect visitors are immediately identifiable by the dense coating of pollen that they carry from flower to flower - a very efficient pollination mechanism which goes a long way towards explaining the high levels of seed production.

Some balsam nectar-addicted visitors, like the wasp above, become so heavily coated in pollen that they develop a ghost-like appearance.