St Mark's Fly

Walk almost anywhere where there is rough grassland on the University estate right now and you will see the air full of jet black flies with long dangling legs. This is the St Mark's fly, so called because it is supposed to appear on St Mark's day (April 25th).  Take this with a pinch of salt however.  This year, the long cold Spring seems to have held them back.  

The dangling leg flight is thought to be all about finding a mate. This settled fly is a male - they have larger eyes that meet together on top of the head. 

Phil Gates' blog  - Beyond the Human Eye (click here) has some excellent close up shots and more information.

The Southern Hawker

Our many ponds and lakes host a good range of dragonflies and damselflies. The most impressive are the large 'hawkers'. These are beginning to be regularly seen now and are worth watching for. They will often be seen away from the ponds, flying strongly over grassland areas and hunting along the woodland edges. Good areas to look include the botanic gardens, the pond and fields to the east of the Mountjoy buildings and the field below the reservoir (on the left as you go up the hill towards Mountjoy). Sightings include the impressive Emperor and this beauty, the Southern Hawker. (click on photo to enlarge.)

Insects on a Mountjoy stroll

If you are based on the Science Site, a 30 minute lunchtime stroll around the sloping field that stretches from the Mountjoy reservoir to the road that leads up to Mountjoy and Biological Sciences is well worth the effort.  Right now, there is a wonderful blaze of colour from the rosebay willow herb.

On the way round, take a little time to stand and stare as the insect life is very active at the moment, especially if you pick a warm still day. Butterflies readily seen include the ringlet (upper surface and underwing shown below)

the meadow brown

and this skipper

The burnet moths are hatching out too.  Unusually, this beautiful moth is a day flier (and one of the most poisonous moths in Britain).

If you search carefully you might find the elegant empty cocoon spun by the burnet caterpillar on a flimsy grass stem.

Leaf hoppers

On the far south side of the University estate, beyond the Botanic Garden and bordering agricultural land leased to Houghall College, is a wonderful area of sheltered rough grassland that blooms with marsh orchids in Spring before the grasses and taller herbs take over about now. Today the area was absolutely alive with thousands upon thousands of this beautiful little insect - the Green Leafhopper Cicadella viridis. As you walk through the grass they leap and bound in front of you propelled by a flick of the hind legs.

The photograph is of a female. Males have darker blue or purple coloured wings.

Leafhoppers make a living by tapping into the sap in grasses.

Insect Activity

Insects are so numerous and varied that it can seem daunting to even begin to get to grips with them. Yet, there are some fascinating insects right under our University noses and their activity is hotting up with the recent warmer weather. For example, walk any of the paths around and over the rough grasslands to the east of the Science Site and Mountjoy at the moment and these two insects should be easy to find and recognise.

The first is the Scorpion fly. An impressive insect, about a couple of centimetres long, it gets its name because the abdomen of the male curls up at the end rather like a scorpion's tail. Worry not, the upturned end isn't a sting at all but the male reproductive organ. The female’s abdomen is more or less straight by comparison. The second example is a soldier beetle. Beetles are easy to recognise from other types of insect in that most have a pair of hard wing covers that meet in a straight line down the centre of the back.

The photograph below shows how the black wing covers open to reveal the folded up wings which the beetle expands for flight.

Damselflies

The large pond behind Mountjoy 4 hosts at least three different species of damselfly, that begin to emerge in large numbers in early June. This is the large red damselfly, one of the commonest species that will breed in small garden ponds.

Damselflies are smaller, more delicate relatives of dragonflies. Most species spend a year as aquatic nymphs before they emerge for their brief lives as adults.

Males and females often have different colour patterns. This is a male common bluetail.

During mating the male grabs the female just behind her head with the tip of his tail and they fly around in tandem before settling. She then bends her tail forward and grasps the back of his thorax, so they assume this 'mating wheel' configuration. This species is the common coenagrion.

 After mating they remain in tandem, while the female lands and dips the tip of her tail in the water, laying eggs on waterweeds or floating debris in shallow water.

Sometimes prime egg-laying sites can be in short supply. Here five pairs of damselflies are egg-laying at the same location, using a floating dead reed as a landing platform.

Speckled Wood Butterfly

Speckled wood butterflies are relatively new arrivals in North East England, first appearing in Durham city three years ago. The species has been gradually advancing northwards for decades - perhaps in response to climate change. There are four known colonies on the university estate - in the Botanic Garden, along the footpath on the east side of John Snow House (sunlit footpaths are a favourite haunt) on the Science Site, on the east side of the hedgerow opposite the Botanic Garden car park entrance and at the southern end of the North American arboretum, on the southern edge of the university estate. Speckled wood butterflies thrive in woodland glades, where the caterpillars feed on common grasses like cock's foot and Yorkshire fog. There are two broods each year and in a good summer occasionally three, so look out for this attractive butterfly in spring, summer and autumn.

Seven-spot ladybird

This little huddle of native 7-spot ladybirds on the Science Site, still hibernating amongst a cluster of wild cherry flower buds that were just beginning to loosen their bud scales in today's sunshine, make a useful comparison with the superficially similar alien harlequin ladybird, which arrived in Durham last year and which you can find out more about here. The red and black-spotted form of the harlequin has more spots, a more domed body and is noticeably larger.... and we'd like to hear from anyone who thinks they've found one.  

Long-horn moth

This little day-flying moths with disproportionately long antennae breeds at several locations on the university estate, including beside the footpath that runs along the east side of John Snow House towards Hollingside Wood and in the Botanic Garden. Its caterpillars feed on dead birch leaves. Only the males have these long antennae, which they use to detect pheromones emitted by females; often, females have a small swarm of eager males fluttering around them.

Tawny Mining Bee

In spring, from mid-April until mid-May, you'll find what appear to be one centimetre-high 'volcanoes' of sandy soil at many locations throughout the university - including the area around the trees outside the library. They are the entrance holes to the nests of this mining bee, which excavates a chamber underground where it lays its egg and provisions it with pollen collected from spring-flowering plants like dandelion.  The larva develops underground on its subterranean food store, pupates and then emerges in the following spring, to begin the cycle again. This species is an important pollinator of fruit trees and also has a fondness for gooseberry blossom.

Banded Agrion Damselfly

Several species of damselfly breed in ponds on the university estate but banded agrion damselflies have so far only been recorded from the small stream that runs from Van mildert college pond and through the southern edge of the Botanic Garden. They are most often seen in late June and July. Only the male has these blue-spotted wings - the female's wings are transparent and her body is a duller shade of green. Both can sometimes be seen resting on the beech tree leaves beside the stream at the point where it runs along the edge of the haymeadow in the Botanic Garden. The males defend a short stretch of territory along the stream and perform a courtship dance in front of the females - an aerial ballet that leads her to the site for egg laying.

Common Darter Dragonfly

On sunny days in July, August and early October you are likely to find common darter dragonflies basking on sun-warmed surfaces around the large pond behind Mountjoy 2, between the science site and the Botanic Garden. Dragonflies' large eyes provide almost wrap-around 360 degree vision and the hundreds of separate lenses in each eye makes they very senisitive to anything moving across their field of vision, but if you approach slowly you can usually get a close look at them. During egg laying the male grips the female behind her head with the tip of his tail and they fly in tandem low over the pond edge, with the female dipping her tail in the water to deposit eggs on waterweeds.

Maybugs

About once every three or four years students living in college are sometimes alarmed by these large beetles that fly in through open windows on late spring evenings in Easter term. They're maybugs, also known as cockchafers, and their grubs feed on the roots of grasses in lawns, taking three or four years to reach maturity, so batches of eggs all tend to reach adulthood at the same time. Maybugs fly with their hard wing covers outstretched and their beating wings make a loud buzz as they clatter around rooms, where they're attracted to lights at dusk. The adults feed on flowers and can be notoriously destructive in orchards in Europe. You can find out more about this large beetle and find photos of its subterranean larva here.

Harlequin Ladybird

Harlequin ladybirds Harmonia axyridis were first found in Durham in November 2009, feeding on ivy flowers near the entrance to Durham University Botanic Garden. On that occasion they were just nibbling harmlessly at the nectar on the surface of an ivy flower, but this is a carnivorous species that has been introduced into Britain and is spreading rapidly. It eats the eggs of many of our native insect species, including other ladybirds, moths and butterflies and could have a significant impact on native insect species biodiversity in Britain. The wing case colour patterns on the harlequin ladybird are astonishingly varied - the example above is the multi-spotted orange morph of the species. A national survey plotting the spread of this invasive species is currently underway and you can confirm identifications and record sightings on-line or by mobile phone by visiting http://www.harlequin-survey.org/default.htm#

Most of the specimens found so far in Durham have been of the red-spotted black form, shown above. The larval stages are larger than other ladybird larvae and have spines on their back. When they are ready to pupate they attach themslves to a leaf by their tail, as the example below has done.

If you spot harlequin ladybirds, which are noticeably larger than most of our native species and have a more rounded outline, Dr. Phil Gates in the School of Biological and Biomedical Sciences p.j.gates@durham.ac.uk would like to hear from you.........

Grassland butterflies

Ringlet

Small Skipper

Small Copper

Wall Brown

Meadow Brown

These are all grassland butterflies, all photographed this summer, that have bred in the area of grassland between Mountjoy 2 and Hollingside wood, on the southern edge of the science site. The ringlet butterflies, whose caterpillars feed on grasses, are fairly recent colonists in the North East, apparently extending their range northwards in response to climate change, and produce one generation per year in late July and early August. The meadow brown – the commonest species here – begins to emerge in late June and has a flight season that extends into early September. The small skipper (seen as an adult butterfly in July) and wall brown butterflies also have larvae that feed on common grass species. The wall browns have two generations, flying in late May and in August and the small coppers, whose caterpillars feed on sorrel leaves, sometimes have three, flying in May, July and early October. So if you take a lunchtime walk through this grassland at any time between May and October there’s a good chance that you’ll see at least one of these species.

Poplar Hawk-moth

This well-camouflaged poplar hawk-moth  Laothoe populi was found roosting on the wall of the Biological Sciences building. Its caterpillars feed on poplar and willow, which are both present nearby on land surrounding the Mountjoy site, so it's likely that this is a breeding species here. For more information on this species visit http://ukmoths.org.uk/show.php?id=28