28 INTRODUCTION. 



(AsiLiD^iE, DoLiCHOPiDiE, SYRPHiDiE, aiicl many groups of 

 MusciDvE) ; some form galls (CECiuoMTiiDiE), some breed in fungi 

 (MYCETOPHYLiDiE and Platypezid.e) ; many are leaf-miners (many 

 Anthomyin.e, most of the Tkypetinje, and some Obtalin^) ; 

 Avhilst the vast majority of the enormous family Muscid.e breed 

 in rotting animal or vegetable matter, as do also many groups of 

 ot-hei- families, in fact this habitat might be considered the most 

 general one in the order. A few are parasitic ; some Bombyliib^ 

 and CoNOPin.E on Orthoptera and Hymenoptera ; the Q^strid^e 

 on Mammalia ; Cyrtiu^ (probably) on spiders. Pupipara are 

 parasitic in the adult state also, on mammals and birds. 



These give only a few of the general habits of the larvae. 



As regards the habitats of the perfect insect it need only be 

 said that a great proportion of the species may be met with 

 almost anywhere on the country-side, although many prefer 

 specially suitable localities, or remain throughout life more or less 

 in the vicinity of their birth, thus, in o)ie way, accounting in 

 conjunction with their environment, for the occurrence of some 

 of the races or varieties. 



The peculiar kinds of situations favoured by each family are 

 mentioned in their proper places. 



4. On the Collecting of Diptera. 



Although some groups of Diptera are sufficiently robust to 

 allow the collector to handle them pretty freely, it w ill be well for 

 him to start with tlie paramount impression that as much care 

 must be taken both in tlieir capture and subsequent treatment as 

 would be required in the case of Microlepidoptera. The delicate 

 pubescence with \Ahich the majority ot the species are covered is 

 easily removed by a careless touch, and such groups as the 

 BoMBYLiin.E, THEREYiDyE, and PsYCHODiD.E require very careful 

 handling on this account. 



In other groups the chief danger is the fragility of the legs ; 

 such are the Tipulidve, Mycetophilid.e, Ci'liciu^e, and C'hirono- 

 TMiD.i:, amongst the Nematocera, and the Leptiuje, Dolichopiu^, 

 'J'achinids and Anthomyids amongst the Brachycera and Cyclo- 

 rrhapha. In other groups again, the delicate spines break off at 

 the least touch (in Sepsin^e for instance), often leaving no 

 trace. 



Numerous methods of collecting are known to all, and the 

 reader is probably already acquainted with many of them. 

 Personally, I have for twenty years collected with the ordinary 

 butteriJy net (white, not green, as it shows up the insects better), 

 capturing the larger specimens singly and then with a little 

 manipulation removing them with the lingers and placing them in 

 a chip or pill-box alive. After a little practice quite a number 

 can be placed in one box, the specimens being brought home alive, 

 and killed without delay by inserting a little powdered naphthaline 



