IN TROD UC TION clxxxv 



the mountain forests about 20 years ago. It would be interesting to compare a number 

 of Hawaiian examples with N. American specimens, to make quite sure of their 

 identity. It is a very favourite prey of the larger Hawaiian Crabronidae. Occasionally, 

 like other parasites of caterpillars, it is itself parasitized by the imported Chalcis 

 obscurata, though the latter is also normally a lepidopterous parasite. Like the 

 Tachinids it may vary greatly in size according to the nature of its host. 



Sarcophagid.'\e. — The species of Sarcophaga are rather numerous and are all 

 unquestionably importations from other countries, and their number has doubtless 

 increased during recent years. Mr F. W. Terry, who has given much time to the 

 study of the species for economic reasons, finds that the male genitalia afford excellent 

 specific characters, but as these have been rarely described by systematists, the identifi- 

 cation of the island species is almost impossible. .S". pallinervis, one of the species 

 described by Thomson from Honolulu, is identical with a North American one, while 

 another is Chinese. S. barbata and 5. dux are also common, but there are now other 

 species present, so closely allied to the former that it is uncertain which of them is 

 really Thomson's barbata. 



These introduced Sarcophaga are now more or less attacked by Hymenopterous 

 parasites, either casually or purposely imported, such as Eucoila, Spalangia, and several 

 species of Pteromalidae, as well as Alysiidae. 



S. pa/linervis is the most ubiquitous of the island species, since the larvae live in 

 the droppings of cattle, and it thrives at all elevations. It is greatly attacked by 

 parasites, and is a favourite prey of the Crabronid wasps. 



Apart from these foreign species of Sarcophaga, the family is represented by two 

 endemic genera, of very great interest, and the most striking in appearance of any of 

 the Hawaiian Diptera. These two genera are closely allied to one another and doubt- 

 less of the same origin, and it may even prove difficult, when all the species have been 

 collected and studied, to maintain the generic distinctions between them. The blacker 

 coloured species of the genus Dyscritomyia have in life a very Tachinid-like appearance 

 and their behaviour in the field is also much like that of some of those parasites. The 

 bright metallic green species of this genus and of Prosthetochaeta are in some cases 

 more Lucilia-like. 



As the development of these genera with their rather numerous and often highly 

 remarkable species showed them, or rather their ancestors, to have been very 

 ancient colonists of the islands, it became a natural question as to what their habits 

 could be. Their Tachinid-like behaviour suggested that they might be parasites of 

 Lepidopterous larvae, but the fact that they were not ever bred from these, though the 

 latter were specially collected in a favourite locality for the flies, made this very uncer- 

 tain. Excrement or carcases of mammals was out of the question from the absence of 

 indigenous mammalia. So too with the birds, for the flies sometimes occur in dry, 



F. H. I. aa 



