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The Fleas (Siphonaptera) of Essex
BY R. S. GEORGE, F.L.S., F.R.E.S.
IT would not be much of an exaggeration to say that almost everyone
can recognise a flea. Many other insects, far more common than
fleas, are quite unknown to the public, yet fleas are rarely studied or
collected. The obvious reason for this neglect is the repugnance with
which these little insects are almost invariably regarded, yet with reason-
able care fleas may be collected with no personal risk to the collector
at all.
Fleas are small, laterally flattened, bloodsucking, wingless insects,
ectoparasitic on mammals and birds. Their larval stages live in the nests
and excrement of the hosts. Many of the species are very host-specific,
though many others have more catholic interests, and to collect the full
range of fleas of a region involves the examination of bodies and nests
and bedding of the bird and mammal fauna of the region. Therefore a
siphonapterist must have a considerable knowledge of these animals and
the co-operation of the local ornithologists and mammalogists. Un-
fortunately he rarely gets this.
The collecting apparatus is simple, a few large tins or polythene
bags, some traps of suitable sizes, a steep-sided bowl, a penknife or a
scalpel, some small cloth bags or a supply of old envelopes, some cotton
reels drilled out for three-quarters of their depth to fit some small glass
tubes, some 70 per cent alcohol (never use formalin), and some
chloroform.
Nest material should be stored in a very tightly sealed tin or bag.
A small portion at a time is put into the bowl, crumpled between the
fingertips and the fleas removed on the damp scalpel tip and put into
the alcohol. The tube will not be knocked over if it is standing in the
cotton reel hole, otherwise accidents will be inevitable and many speci-
mens will be lost. Each portion of nest material should be handled
several times for many adults lie dormant in their cocoons until
physically disturbed—then they emerge. Finally the tube should contain
a note, written either in pencil or Indian ink, giving: the fact that
the collection came from a nest, the identity of the nest-owner, if known,
locality, date, altitude (in mountainous areas), the collector's name.
Mammalian bodies are most easily examined after death or during
unconsciousness. This means shooting or trapping the hosts. Trapping
small rodents and shrews is most conveniently done with nipper traps
set in a trapping line. For easy finding traps should be marked with a
piece of wool or a twist of grass and need examination as late as
possible at night and as early as possible after dawn. Fleas move
towards small air movements and thus great caution must be taken when
collecting bodies. My procedure is: I place an old envelope, widely
open, near the trap, very gently lift the trap and body and place inside