18 STRATIOMYID/E. 



usual. Prsefui'ca originating in this family about opposite base 

 of discal cell (except in Behin.t; and Xi'LOMiixiii), whereas in all 

 otiier families of Buachycera it originates much sooner. In 

 Berin.i; and Xylojiyiism: all the veins attain the Ming-niargiu ;* 

 praefurca quite distinct ; costa nearl}'^ or quite reaching wing-tip ; 

 ambient vein more or less distinct ; 4th posterior cell closed in 

 Xylomyin^. In all subfamilies, membrane of wing always ribbed 

 or wrinkled ; squamae variable in size, thoracic pair sometimes 

 absent. 



The Stratiomyid.e are invariably bare of bristles or spines 

 (except the side thoracic spines in a few genex'a), but often possess 

 dense soft pubescence extending over the whole body and thw 

 femora. The crowding together of the anterior veins and the 

 extremely wide variation of form in the antenna) (perhaps greater 

 than in any other family of Diptera) are their principal characters. 

 In the Berin.?! and Xylomyin^^ the venation takes the form of 

 the other allied families and the antenna) are more uniformly 

 constructed, elongate or subconical, with distinctly aniuilated 

 3rd joint. The family is closely allied to the LEPXiDyE and 

 TAisANiDyE aud to the small family of gigantic flies, the Acan- 

 THOMERiD^, known only from South America. 



Life-liistorij . — The larvae show considerable variation, though 

 easily recognised when once seen, and those of some species are 

 popularly known as rat-tailed maggots, as are also those of the 

 Eristalin.e. They are 12-segmented, including head, hemi- 

 cephalous or conical, very elongate, rather leather}^ and more or 

 less flattened. They live in earth, dung, semi-liquid or decaying 

 matter, and many are aquatic ; in the latter case the eggs are laid 

 on plants above the surface of the water. No pseudopods ; 

 terminal spiracles not visible, placed wholly inside a chamber 

 which has generally a closed or obscure aperture. Pupa coarctate, 

 in which character this family differs from all other Brachycera, 

 the imago escaping through transverse slits on the 3rd and 5th 

 segment and a longitudinal slit between them. 



Many species hibernate in North Europe, but very possibly do 

 not do so in the Tropics. The life-histories of several European 

 species are well knovvn. The imagines frequent grass and low 

 herbage in marshy situations and, generally speaking, are sluggish 

 in habits, though some have a very rapid flight in hot sunshine. f 



Table of Subfamilies. 



1. Abdomeu of at least seveu obvious segments. ... 2. 

 Abdomen of five, or at most six, segments 3. 



2. Prjefiuca beginning at about opposite base of 



disoal cell : 4th posterior cell wide open .... Bkrin.'e, p. 89. 

 Praifurca begiriiiing considerably before base of [p. 96. 



dihcal cell ; 4tii posterior cell closed Xylomyin-s?, 



* Except fur tm aborlivp branch of the 4th vein in some BERiNiK. 

 + Additional and more detailed information occurs under the various sub- 

 families or genera concerned. 



