A study of the flora and fauna in disused Causeway and Charringtons House car parks in Bishop’s Stortford town centre

Nature Notes columnist Jono Forgham covers your fortnightly look at nature around Bishop’s Stortford

There has been much discussion on social media about plans for the disused Causeway and Charringtons House car parks. A Sunday car boot sale, whilst not perhaps visionary, appears to be proving popular with local residents.

I thought it would be fun to carry out a survey of what is present on this small site with a view to finding some rarities that could lead to it being designated a Site of Scientific Special Interest (SSSI.) Now that would put the proverbial cat among the pigeons that are the local councils!

Of course, this was never going to be the case, but I enjoyed wandering around the tarmac expanse, checking the vegetation for urban wildlife and trying to grab photos of what I discovered. Consequently, I started by looking closely at the hedgerow that borders the Waitrose car park.

Many of the trees and shrubs here are non-native and therefore offer little in the way of larval food plants for moths, butterflies and fly species, but, in amongst the thorny olive, Italian alder, pyracantha and cotoneaster, there were examples of Norway maple on which I noted a fair few leaf mines of the micro moth Stigmella aceris. This small moth has taken to using this tree as a food plant due to its similarity with the original food, field maple.

On the leaves of several shrubs were examples of a Lucillia species of blowfly, also known as greenbottles, their metallic green thorax and abdomen glistening in the bright and warm sunshine. A small white butterfly weaved its way around the shrubs before settling upon a flowering pink briar rose.

I checked more trees and discovered both whitebeam and holm oak to be present. The latter is also called the evergreen oak and at this time of the year holds plenty of acorns in deep cups. Unripe berries dangled from the whitebeams, potential food for nocturnal moths when they become rotten after the first frosts later in the year.

Most of the low hedgerows held much discarded litter which makes this site somewhat unsightly at present. Near a cider can, a plastic fork and a sign saying “sunglasses £1” was a good stand of thorny olive, which, after a closer inspection, was clearly still in flower. It showed small and delicate white bell-shaped flowers that were certainly attracting the attention of hoverfly and bee species, so I settled down to see what was nectaring upon these flowers. First to arrive was an Apis mellifera, the western honeybee, closely followed by the bulkier Bombus lucorum, the white-tailed bumblebee. These tiny flowers only had a small amount of nectar as the bees invariably moved on very quickly from one flower to the next, making macro photographs a little difficult.

Syrphus species of hoverfly were also present as was the darker Eristalis tenax, a bit of a bumblebee mimic. A tiny Lonchaeidae fly, a lance fly, alighted upon a lime leaf. These limes can be found along the side of Charringtons House and a study of the leaf showed them to hold gall mites. These tiny mites inject a chemical into the leaf that causes the upper surface to grow a gall in which the mites live, feeding upon the leaf sap.

By now I had reached the side of the car park that runs parallel to The Causeway and here encountered good stands of a variety of roses, many laden with rose hips which will feed insects once they have softened and started to rot. A wren fired off its staccato alarm call and a robin darted for cover.

I was looking so intently at the shrubs that I failed to note a series of metal barriers which I walked straight into! Sore knees, but it did make me stop and I was pleased I did as, under some roses, there was a small patch of ivy which was just coming into flower. A most popular flower that attracts many insects and this example was alive with flies, wasps, bees and hoverflies.

A bright yellow and black Myathropa florea hoverfly was busy feeding. This colourful insect has the nickname the Batman hoverfly due to markings upon the thorax that are not dissimilar to the Batman logo. Several Vespula vulgaris, the common wasp, were feeding upon the flowers whilst also hunting for prey, such as small flies.

The star of this group was Colletes hederae, the ivy bee, showing its black and yellow hooped pattern. This bee was only described as new to science in 1993, although it has been present over much of Europe as from the 1970s it was thought to be another Colletes species. It was first recorded on the UK mainland in 2001 in Dorset and has spread rapidly from there. At this time of the year it is likely to be found on most stands of ivy growing locally. It was first recorded in north Norfolk in 2014 and is now well established across the South East. Another bee that dropped by was Bombus pascuorum, the common carder bee.

Following finding the ivy I came across a row of elms where I searched the leaves for signs of the splendidly-named zig zag sawfly, a pest species, but none was apparent. However, I discovered the leaf mine of another micro moth, Stigmella lemniscella.

Leaf mines are created by some micro moths as well as a few bee and beetle species and plenty of tiny fly species. The egg is laid upon the leaf and the tiny caterpillar eats its way into the leaf, residing between the upper and lower layers of the epidermis. It then munches its way around the leaf, often leaving a tunnel-type pattern that increases in width as the caterpillar puts on weight. By looking at the pattern made by this eating, knowing the leaf species and checking whether the egg was laid on the upper or lower part of the leaf, it can be possible to name the caterpillar to a species. On other occasions it is necessary to keep the leaf until the moth emerges as an adult.

Another Eristalis hoverfly species got into the act at this point, but rested at an awkward angle which made for a pleasing photo but didn’t permit me a good enough view to distinguish which precise species. In the corner by Waitrose, a lone large bindweed was still in flower, whilst growing out of an iron grid was the hardy ribwort plantain.

I decided to go around again to see what I could add to the list, looking carefully at the helicopter seeds upon the Norway maple for signs of a moth caterpillar that feeds inside the actual seed, but these were not ripe enough yet to show the tell-tale marks. I encountered a low-growing English oak that must have self seeded or the acorn had been buried by a grey squirrel, perhaps.

On a sticky bud were plenty of small black ants, Lasius niger, feeding upon the sap. A pair of wood pigeons waddled around the deserted tarmac as an inquisitive car park attendant came over to see what I was up to. When I said that I was looking for insects to photograph, he looked at me somewhat quizzically and departed. Several other people passing by also inquired as to what I was up to and I managed a quick chat with David, a chap I hadn’t seen for a few years, so pleasant to bump into him.

One final check on the Italian alder to see if anything was using this non-native tree, but nothing. The cones were set but not yet mature. When they are, they offer seed food to siskins, a finch that migrates to our shores from Scandinavia in winter and is a specialist alder feeder. You can usually find large flocks of them around Grange Paddocks where there are many alders.

I took a few general photos of the area and headed back to the car. Nothing unexpected was discovered, which is what I had anticipated, but I was pleased with what I did find.

Nature frequently does not like tidy: well-mown lawns, tidy hedgerows and trees not associated with our island can be barren habitats for nature, whereas a disused car park can be a place where nature will move in.

Give this area five years of freedom to develop and, who knows, we could have an urban nature reserve in the middle of the town!

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