Bush crickets on the menu
Graham Smith 48 The Meads, Ingatestone, Essex CM4 OAE
During a visit to Great Edney Field, Writtle Park (TL660035) on August 1st this year I
disturbed several free-flying crickets which proved, on being netted, to be Roesel's
Bush Crickets Metrioptera roeselii. Both were of the long-winged form which both
Wake (1997) and Gardiner (2005) state is infrequently recorded in Essex, most often
occurring in long hot summers. As readers will be aware this is not a description that
could readily be applied to the summer of 2007!
Great Edney Field is a place where I like to sit on a summer's day and watch the world
go by. It is long term set aside grassland formerly occupied by ancient woodland, grubbed
out and converted to arable land in the late 1960s. While thus engaged I noticed many
more crickets on the wing - their flight ponderous and straight with no apparent means
of steering to left or right - the legs protruding behind their bodies like twin tails. I
watched them for some time and noticed that although, initially, they remained fairly
low to the ground many would suddenly gain height and soon disappear out of binocular
vision. It was hard to tell whether this was a deliberate act or whether they simply hit
pockets of rising air, the resulting ascent being beyond their control. I suspect the latter
as one second they were trundling along close to the ground, the next they were
disappearing rapidly into the firmament! On the other hand, I presume (perhaps
incorrectly) that the appearance of so many long winged individuals may be in response
to population pressure and that the aerobatics described above are a normal dispersal
strategy. It was while watching this spectacle that I noticed a pair of Hobbys - rapidly
followed by a second pair - feeding on flying insects high above the field. The assumption
is, when you see these falcons behaving in this way, that they are catching dragonflies.
However, they need all their well known aerial skills to catch these insects whereas on
this occasion they were feeding as if indolently plucking apples off a tree! Also, both
Common Darters and Migrant Hawkers - which are their principal prey at this season -
have been very thin on the ground this summer, the latter, as is usual, having only recently
arrived in the area. Still, it is easy to put two and two together and make five! It was not
until a couple of Kestrels joined in, at a much lower height, that I could confirm that at
least some of the insects being caught were crickets. Like the Hobbys, they would pluck
an insect out of the air, reach down and partially dismember it, then swallow what was
left. In the case of dragonflies they remove the wings, with the crickets it may well have
been their legs, although that is speculation! Eventually, one of the Hobbys descended
low over the field and was also observed catching crickets.
All six raptors had been feeding fairly steadily for about an hour - with breaks - when
around sixty Black-headed Gulls and a single Common Gull arrived on the scene and
began feeding, circling lazily above the field and making occasional forays to snatch
their prey. The assumption with gulls is that they are feeding on flying ants but a walk
8 Essex Field Club Newsletter No. 54, September 2007