Diptera at Hylands Park
Del Smith & Mark Hanson
Introduction
The following chapter is based on Diptera recording undertaken at Hylands in the years 2001 -
2003. All the flies were collected by M.W.Hanson, for the most part using a net (a brief trial with a
malaise trap was unsuccessful due to the public nature of the park) and a small amount of material
was reared. The pinned material (apart from Syrphids) was subsequently determined by Del Smith.
Particular attention was paid to the Diptera associated with the older trees in the park, in order to
establish some idea of the conservation status of the site. Between 2001 and 2003. a total of 337
species of Diptera were recorded. In the appended list, species associated with the older trees
(Saproxylics) are followed by the letter 'S:. The national conservation status (currently under review)
of species is also added (either N = Notable or RDB = Red Data Book 1, 2 or 3). Despite 330 plus
species being found. I suspect that the real total of Diptera species that could potentially be found
in the park to be nearer the thousand mark, because of the diversity of habitat and also the rich
variety of trees, shrubs and higher plants. A total of 17 nationally notable and four Red Data Book
flics were recorded from the site. A minimum of 71 Saproxylic species were found.
Scarce and Unusual Species
The most notable species of fly from Hylands is the spectacular hoverfly Callicera spinolae. This
species, along with the bumble-bee, mimic Criorhina ranunculi and the small Sepsid Fly Themira
gracilis were all recorded as new to Essex. Criorhina ranunculi observed twice at rot-holes at the
base of Horse Chestnut trees and once on the blossom of Cockspur Thorn (Crataegus crus-galli) is
a very plausible bee mimic and with a very early flight season, is probably under-recorded in
Essex. Themira gracilis, another nationally notable species with an apparently very disjunct
distribution in Britain, being known mainly from the north of England and Scotland and then in the
south in Hampshire and now in Essex, was swept from the edge of the Serpentine Lake in July
2002.
Callicera aurata (RDB 3) - another of the rare hoverflies, but more often recorded than the RDB 1
C. spinolae - was found at rest on an Ivy leaf in the formal gardens on September 12th 2002. Its
larva, along with those of C. spinolae, have been recorded from rot-holes in various mature tree
species. At Hylands it would almost certainly occur in Horse Chestnut. Psilota anthracina (RDB
2) is possibly the classic parkland hoverfly in Essex. It is known from Weald, Thorndon and Dagnam
Parks, as well as Hylands. Elsewhere it also occurs in old forests, such as Windsor. Didea fasciata
is a rarity in Essex, known only from a handful of sites. In Britain it is often recorded from ancient
woodland, but is also found in secondary woodland and even gardens.
Dorycera graminum (RDB 3) is, as its specific name suggests, a grassland species. Although rarely
recorded, in 2002-3 it has turned-up at several sites, mainly in south Essex and occasionally in
large numbers. I noted a single specimen on grass near the Serpentine Lake in 2003.
Further Recording
Much more recording of Diptera needs to be undertaken, despite some 337 species from 61 families
having so far been found. Even the hoverflies, die best studied group, have some notable gaps.
Essex Parks: Section 2 - Hylands Park
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