Bath City Farm, 8 June 2024

This year’s walk at Bath City Farm took place on 8th June, led by Mike Williams, the farm’s ecologist. Attendance was slim, but the composition allowed us to focus mainly on invertebrates, of which over 800 species have been recorded on the farm since 2016.

We began by examining some recently-excavated fossils of Trigonia, a marine mollusc from the Jurassic Period, which had been discovered during the construction of the farm’s new hay barn. Back then, Bath was underwater, and the limestone rocks that have shaped the landscape and the ecology of our area were laid down on the sea bed. Before heading off to the fields and woods, a potter about in the garden area yielded a red form of Brassica Bug (Eurydema oleracea), the hoverfly Chrysotoxum cautum, and the opportunity to observe the courtship dance of a male Pardosa sp. wolf spider as it approached a female. The female was already carrying an egg sac and had therefore already mated, but the male seemed unconcerned by this.

We also took time to examine the plants on the newly-created butterfly bank, which included Kidney Vetch (Anthyllis vulneraria), which is now uncommon in the wild in Bath.

Wandering through one of the top meadows we spotted a small number of common species, but nothing particularly of note. Venturing into the woodland, we came across a Jersey Tiger caterpillar under a log, and stopped to admire the recently-created woodland pollinator garden.

The central field at the bottom of the farm (Maiden Furlong), was by far the most interesting. The first species of note was a Welsh Chafer (Hoplia philanthus), a beetle that is becoming increasingly frequent in Bath. The dragonfly highlight in this field was a male Scarce Chaser (Libellula fulva). This species breeds on the river, but small numbers are found on the farm in most years. Flies included the Marsh Snipefly (Rhagio tringarius), Ferruginous Bee-grabber (Sicus ferrugineus), Two-banded Spearhorn (Chrysotoxum bicinctum), and the Four-barred Major Soldierfly (Oxycera rara) – a new record for the site.

This species is likely associated with the prominent wet flush in the field. The wet flush is notable for its abundance of Water Figwort and associated insects. The solitary wasp Symmorphus gracilis was present, as were its main prey, the larvae of Cionus weevils (three species of which have been found here). Notably absent were the huge wasp-mimicking Figwort Sawflies (Tenthredo scrophulariae), which can be abundant here in some years – although one was spotted two days earlier.

Moving on to the pond, we caught a glimpse of a Palmate Newt (Lissotriton helveticus), of which about 130 were recorded during a survey earlier in the year. A second new soldierfly species for the farm’s list was recorded here, the Black Colonel (Odontomyia tigrina).

The walk ended with a visit to the territory of a two year-old tame Robin (Erithacus rubecula), which Mike has been documenting the life of since it was a fledgling, and its parents before that. He was very busy collecting food for his mate, and was grateful for the offering of mealworms.

With a number of conservation measures in the process of being implemented on the farm, hopefully in future years this site will continue to yield interesting records.

Mike Williams