PREFACE 



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 is quite out of date and inconsistent with the knowledge of the 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. 



It 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 (" Dipteres 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 



