506 DIPTERA 



CHAP. 



of the body as in the Scutellerid Hemiptera : the wings are 

 entirely concealed, and the abdomen is reduced to a plate, with 

 its orifice beneath, not terminal ; the surface of the body is 

 highly polished and destitute of bristles. Whether this is a 

 mimetic form, occurring in association with similar -looking 

 Bugs is not known. The North American genus Toxotrypana 

 is furnished with a long ovipositor ; and in this and in the shape 

 of the body resembles the parasitic Hymeuoptera. This genus 

 was placed by Gerstaecker in Ortalidae, but is considered by 

 later writers to be a member of the Trypetidae. This latter 

 family is of considerable extent, and is remarkable amongst the 

 Diptera for the way in which the wings of many of its members 

 are ornamented by an elaborate system of spots or marks, vary- 

 ing according to the species. 



Fam. 34. Anthomyiidae. Flies similar in appearance to 

 the House-fly ; the main vein posterior to the middle of the u"i ag 

 (4th longitudinal) continued straight to the margin, not turned 

 upwards. Eyes of the male frequently large and contiguous, 

 bristle of antenna either feathery or bare. This very large family 

 of flies is one of the most difficult and unattractive of the Order. 

 Many of its members come close to the Acalyptrate Muscidae 

 from which they are distinguished by the fact that a well- 

 developed squama covers the halteres ; others come quite as 

 close to the Tachinidae, Muscidae and Sarcophagidae, but may 

 readily be separated by the simple, not angulate, main vein 

 of the wing. The larval habits are varied. Many attack 

 vegetables, produce disintegration in them, thus facilitating de- 

 composition. Anthomyia brassicae is renowned amongst market 

 gardeners on account of its destructive habits. A. cana, on the 

 contrary, is beneficial by destroying the migratory Locust 

 Schistocerca peregrina ; and in North America, A. angustifrons 

 performs a similar office with Calopteniis spretus. One or two 

 species have been found living in birds; in one case on the head of 

 a species of Spermopliila, in another case on a tumour of the wing 

 of a Woodpecker. Hylemyia strigosa, a dung-frequenting species, 

 has the peculiar habit of producing living larvae, one at a time ; 

 these larvae are so large that it would be supposed they are full 

 grown, but this is not the case, they are really only in the first 

 stage, an unusual amount of growth being accomplished in this 

 stadium. Spilogaster angelicae, on the other hand, according to 



