notes indicate that he observed it in Epping Forest on one occasion in 1937. but it was
still regarded as rare and a new species to the Forest in the report on the Cuckoo Pits
Survey (Pinniger. 1945). Pinniger also expressed the view that 0. cancellatum might be
breeding in nearby bomb-craters. Longfield (1949b) gave Hainault Forest as a locality,
but commented that for 'some unexplained reason' it had only been recorded in Epping
Forest on two occasions. In fact, there is a specimen collected by E. S. Brown from the
Forest in 1947 in the Hope Department collection, and this, together with Pinniger's and
Hammond's sightings suggests that it was somewhat more frequent in the Forest by the
end of the 1940s than Longfield thought. It had also been observed by D. A. Ashwell at
Hatfield Forest, and there are extant specimens dating from 1940 (Hope Department).
Pinniger, Syms and Ward (1950) reported 1949 sightings of the species from Hatfield
Forest and from two separate sites in Epping Forest, and there are. further, specimens in
Queen Elizabeth's Hunting Lodge Museum collected by B. T. Ward from Hatfield
Forest (1949) and Grays (1950). There were subsequent reports during the 1970s from
various sites in Epping Forest by J. Owen-Mountford. Hammond and others.
The historical record suggests that the species may not have been established in Essex
before the mid 1930s, but that it became established in a number of west Essex localities
between that time and the late 1940s. Given this species' adeptness at colonising newly
created sites, it seems likely that, as Pinniger suggested, its establishment in Essex was
aided by the numerous war-time bomb-craters. The dearth of records between 1950 and
1980 reflects a shortage of observers, rather than a decline of the species, as the results of
the current survey show. It is now well established and generally common in coastal
ditches, flooded pits, rivers, canals and lakes in north-east, central, south and west
Essex. So far it has not been recorded from the north-west. In all it has been recorded
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