166 Tachinidae. 



anteriorly than most other Tachinid larvæ. The posterior cavity 

 with the spiracular piates is well developed and surrounded by a 

 wall with twelve pointed warts; anus lies ventrally as a longitudinal 

 opening with a spiny papilla on each side. These larval characters 

 are also visible on the puparium. The species are viviparous. The 

 larvæ are mainly saprophagous, living in dung and human excre- 

 ments, and in decaying vegetable and animal matter, carrion, dead 

 insects and snails and the like, and are thus rather polyphagous. 

 Some species, however, may often occur in great numbers by strong 

 attacks of injurious Lepidoptera^ especially Lymantria monacha and 

 Dendrolimus pin i, and they eat here no doubt sick larvæ and pupæ, 

 but they have also been bred numerously from pupæ of the said 

 Lepidoptera; it would thus be quite doubtless that they are para- 

 sites, were it not that experiments with infesting sound larvæ with 

 Sarcophagas have always been negative. The question is not yet 

 solved. Probably the Sarcophagas have not yet been true parasites 

 but are beginning to develop in this direction. Some species seem 

 parasitic in other ways, thus dathrata has been bred from eggs of 

 Epeira and haemorrhoa from snails. Species are further recorded 

 parasitic on Acridiids, Oryctes^ and Melolontha, but probably are 

 here not true parasites. Larvæ have sometimes been present in the 

 intestine of man, but this is accidentally. 



Of the genus a very large number of species is known; Bottcher 

 in 1913 records ca. 75 European species, and several have been 

 described since then; the number may be near a hundred; 24 have 

 hitherto been found in Denmark. 



The discrimination of the species of this large genus was until 

 later years very unsatisfactory, viz until first Pandellé and later 

 on Kramer, Villeneuve and especially Bottcher undertook a study 

 of the male genitalia, and showed that in this way a sure distinction 

 of the males was possible. The genus is so difficult because the nume- 

 rous species are all almost quite alike in colour and whole outer 

 appearance, and also because the single species may vary extremely 

 in size. In the following descriptions the colour and other common 

 characters will only be shortly mentioned, and I shall therefore give 

 an account of these characters. The colour is grey, varying to bluish 

 or yellowish grey or yellowish. Thorax has three black stripes, pro- 

 duced on scutellum, and besides a shorter stripe is present at the 

 lateral margins. To each side of the median stripe, anterior to the 

 suture, a narrow, less distinct stripe is seen. Abdomen shows the 



