PREFACE. 
as 
7 
THE reason I undertook to publish this book was the almost total 
absence of any treatise in English upon this much-neglected order of 
insects. I have dealt with most of the species indigenous to the 
British Isles, and with many points of general interest relating to the 
order of *‘ Flies,” also with the characteristics of families and genera, 
and, where possible, with the life histories of the various groups, 
especially of those that are injurious to our crops and farm stock. 
The only English work published on this subject is Walker's 
‘“‘Insecta Britannica Diptera,” which is now out of print. It was 
written more than fifty years ago, and naturally contains much that 
is quite out of date and inconsistent with the knowledge of the 
present day. 
t is hoped that this account may in some way fill up this gap in 
entomological literature. The author trusts he will be pardoned for 
the many discrepancies that may have crept in, owing in many 
instances to his imperfect knowledge of the languages in which most 
of the literature on this subject is written. For those who wish to go 
more fully into the subject, the larger works of Meigen (“ Zwei- 
flugelige Insecten”), Macquart (“‘ Diptéres exotique”), and Schiner 
(Fauna Austriaca”), together with the numerous papers, articles, 
and pamphlets enumerated at the end of each family, may be 
consulted. 
In a small work of this kind it is impossible to give a detailed 
description of all the species recorded as British. I have there- 
fore chosen those about which there seems no doubt, and have 
omitted many mentioned by Walker as being doubtful. The 
