5o Memoirs of the Indian Museum. [Voi,. Ill, 



27. Axillary cell : at the base of the hind margin, between sixth vein and hind 

 margin of the wing ; this cell is partly fused with the preceding and with the 

 axillary lobe. 



The pattern of the wings is also important for the distinction of the species and 

 even of the genera ; but in this last case some caution is necessary. The colouring 

 is usually due to a diffused tint in the wing-membrane itself, but in some cases, 

 as in the genera Schistopterum and Rhabdochaeta , it is due to microscopic peculiarly- 

 shaped and coloured hairs of the wing surface. The patterns may be reduced to two 

 principal types, the banded type and the reticulate type ; rarely these two types are 

 to be found on the same wing, as in Acrotaenia. 



The banded type is well-developed in the so-called '^ rivulets ' ' of many species ; 

 an exaggeration of this type is shown by the species which have black wings, with 

 hyaline indentations and spots, or with complete apical bands. The species which 

 have entirely black wings, with scattered, rather distant, hyaline or subhyaline 

 spots show passage to the following type. 



The reticulated type is due to the presence of numerous approximate hyaline 

 spots, which break up the black colouring of the wing into a net-like pattern ; on 

 account of the form and size of these spots the net can be more or less closed, and 

 sometimes quite broken up into brown isolated streaks. Special cases of this type 

 are the so-called " star-shaped pattern " and the '' radiating pattern." 



The colouring of the pattern varies from yellow or brown to black; in rare 

 instances red spots are to be observed, as in Schistopterum. 



3. METAMORPHOSIS AND BIONOMICS. 



Very Httle is known of the early stages and bionomics of Indian Trypaneids; 

 but I think it useful to give here a summarized account of those of the family in 

 general. 



The Trypaneids are flies which live only on vegetable substances, the adults run- 

 ning on leaves or feeding on flowers, the larvae living in various parts of vegetables. 

 The metamorphoses of many species are well enough known, chiefly because some 

 species are very serious pests, while some others can be easily obtained by rearing. 



The adult flies are to be found on plants, chiefly on those in which they have 

 been living in the first stages ; most of the true Trypaneininae are to be seen on 

 plants of the family Compositae. Other species visit flowers ; and many of the 

 Dacinae and of the Ceratitinae seek the sweet secretions and exudations of plants 

 or of certain insects such as the Coccidae. 



The flies are remarkable for their handsome aspect and specially for the 

 patterned wings, which they hold spread and trembling A great many species 

 prefer shady and cool places, and are to be found on the under surface of broad 

 leaves. Many species, which are easily observed in the larval stages, are extremely 

 rare as adult flies, and these can be obtained only by breeding. 



The females, with their corneous ovipositors, place the eggs in suitable parts of 

 the vegetables and the very variable form and length of the ovipositor denotes that 



