80 THE ESSEX NATURALIST
printed labels inscribed 'Colchester. W. H. Harwood', with no date of
capture. These are presumably specimens presented to the Museum by the
elder Harwood during his lifetime.
The Harwoods seem to have done little or no collecting in south Essex,
and, apart from a very few isolated references in the entomological
journals to Epping Forest, Brentwood and Benfleet, we know next to
nothing of the Syrphidae of Essex between the two World Wars. But from
1940 onwards a number of Dipterists have visited Epping Forest and the
Thames marshes between Benfleet and Leigh-on-Sea, and very recently
there has been some more widespread collecting and observation of
Hover-Flies, with particular attention being paid to the Reserves owned
or managed by the Essex Naturalists' Trust. However, there are still large
areas of the county which are virtually unknown so far as Diptera are
concerned.
Sources of Unpublished Records
Records supported by specimens in the three museums mentioned above
are indicated by the following abbreviations: BM British Museum
(Natural History), HD Hope Department, PE Passmore Edwards Museum.
Records deriving from L. Parmenter's and C. N. Colyer's personal records
now held at the British Museum (Nat. Hist.) are indicated by LP and
CNC respectively.
A number of entomologists have kindly assisted me in the preparation
of this paper by contributing their unpublished records, or allowing me to
look through their collections of Diptera, and I am greatly indebted to
them: A. A. Allen, R. H. Allen, P. J. Chandler, D. G. Down, G. Glombek,
C. O. Hammond, A. W. Jones, E. T. Levy, E. H. Moss, A. W. Pearcy,
G. A. Pyman and J. F. Shillito.
Records which appear without any ascription are my own.
Summary of Essex Fauna
Of the 240 species of Syrphidae at present known in Britain there are,
with the publication of this paper, records of 157 species in Essex, though
25 of these are not known to have occurred in the county since the Harwood
era, i.e. for at least 50 years, and one (Arctophila fulva) not for 200 years.
It is of interest that in a recent exhaustive paper on the Kent Hover-Flies
Chandler (1969) records 183 species from that county. Some of the Kent
Syrphids are restricted to chalk downland, and others to coastal sand-
dunes—both types of habitat scarcely to be found in Essex—but there are
probably a few Hover-Flies not yet recorded from Essex which will turn
up in our county, and a number of those not recently found may be
expected to be re-discovered. Perhaps the most likely additions to our list
are Rhingia rostrata, Pipiza lugubris and some of the Cheilosia species
which are difficult to distinguish in the field.
Migration
Distribution of Syrphidae is to some extent affected by the known
migratory habits of some of the larger species. Verrall (1901) refers to 'a
countless swarm of Syrphi' at Walton-on-Naze on 24 August 1869,