Vol 10 Part 14. An introduction to the immature stages of British Flies ...

To facilitate approximate identification a range of pupae and puparia is illustrated
(figs 1109-1286) for most families. Brauns (1954b) is useful for terrestrial species and
other works dealing substantially with pupae are indicated under the appropriate
families (see Ferrar, 1987 for Cyclorrhapha).
Classification, nomenclature and use of keys
As far possible the sequence of families, subfamilies, tribes and genera follows that of
the Diptera Check List (Smith et al., 1976) for the convenience of users of the Handbook
series. Sometimes the only workable keys to larvae are based on a classification different
from that now used for the adults (e.g. Syrphidae) and in such cases explanatory
comments are given. Where recent taxonomic research on adults has led to changes in
the nomenclature, status, or generic placing of well-known species (such as pests)
adequate synonymy is cited under the appropriate family treatment. Colloquial names
for pest species, plant crops and other familiar plants and animals are given in addition
to their scientific names at the first (or most important) citation.
In using the keys it should constantly be borne in mind that many genera, species and
even some families are unknown in the immature stages and therefore the full range of
morphological variety is unknown. Particularly in the Acalyptratae couplets may lead
to a choice of families and several families run through to more than one place in the
keys. It is intended that identifications should be attempted by combining use of the
keys with a consideration of habitat and pabulum (using the introductory sections in
combination with the index) in conjunction with the figures. In this way it should be
possible to identify many of the Diptera most commonly found as larvae or pupae,
including all species of economic, agricultural, medical and veterinary importance. As
far as possible I have aimed to include all those Diptera whose immature stages are
regularly submitted to entomologists as 'economic enquiries'.
Notes on the illustrations
'As far as I am a judge, nothing would recommend entomology more than
some neat plates that should well express the generic distinctions of insects
according to Linnaeus; for I am well assured that many people would study
insects, could they set out with a more adequate notion of those distinctions
than can be conveyed at first by words alone.'
Gilbert White, 1771
The illustrations are meant to supplement the text with the following aims:
(I) facilitating identification as far as family and tribe in conjunction with the keys;
(2) to show the range of form and to illustrate particular environmental adaptations;
(3) to facilitate the identification to genus and species of selected Diptera such as pest
species, well known 'text-book' species and common readily encountered species of
value for teaching or demonstration, or frequently found during faunistic surveys.
Attempts at identification by perusal of the whole insect figures alone should be
practised with extreme caution making particular scrutiny of structural details and
scanning all the figures. Convergence through adaptations to similar environmental
requirements may result in remarkably similar superficial appearances between several
taxonomically widely separated species, e.g. compare figs 1027 and 1059; figs 239 and
903; figs 20 I, 617 and 938 etc.
Allowance should be made for some variation in the structures illustrated, particularly
in the pigmentation of the cephalopharyngeal skeleton. Apart from some
expected variation within a species there is evidence of geographic variation. Published
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