The flies (Diptera) of Sata Pond and Reservoir Pond were surveyed between May and August. Both water bodies and their associated vegetation produced an interesting range of diptera, but clearly many of the recorded species were attracted from elsewhere to nectar sources provided by pond and surrounding vegetation. Examples are woodland edge species such as the hover-flies Leucozona luconim and Xylota segnis, and the bee-fly Bombylius major. Species typical of marsh and fen include the soldier-flies Nemotelus nigrinus with presumed amphibious larvae, Opiodontha viridula with aquatic larvae, and in the hover-flies the two Pyrophaena species, together with Lejogaster metallina and the three Anisimyia species. The latter are often found in association with tall emergent vegetation.
174 species were recorded, almost all the species are common and widespread, but s ix of these have the status of Nationally Scarce.
The crane-fly Phalacrocera replicata (Nb) is known from several widely scattered bog and fen sites in Yorkshire (e.g. Malham Tarn, Thome Moors, Skipwith and Strensall Commons). This is the first record for north-east Yorkshire (v.c.62).
Pilaria scutellata (Nb) is recorded from only three other Yorkshire sites, all of them being post-1976 (Throxenby Pond, Scarborough; Bentley Common, Doncaster, and Gypsy Marsh, Bamsley). Nationally it is widely scattered across Britain, where it is usually associated with semi-bare humic mud or peat on acid soils or poor fen.
There is a small cluster of records from south Yorkshire for Helms pallirostris (Nb) (Parkland Lake only), and this is the first for north-east Yorkshire (v.c.62). It occurs nationally in a wide range of wetland sites (it is especially frequent on the North Kent marshes!).
A single male example of the hover-fly Xanthandrus comtus was flying around flowers at the edge of the pond. It has no known affinity for wetland sites and was clearly a wanderer - indeed, it has recently been conjectured that this may be a migrant species. There appear to be only one or two recent records of this species in Yorkshire, and whilst the Sata Pond finding is most gratifying it is probably of little significance.
The only non-dipteron of note was the hemipteran Polymerus palustris. This pretty bug is associated with marsh bedstraw (Galium paJustre) and it appears to be established at Sata Pond. It is known from a number of widely scattered localities in Yorkshire, including Askham Bog, Wheldrake Ings and Thorne Moors. |
