28 INTRODUCTION. 



DOLICHOPIDJE, SYEPHiD^;, and many groups of 

 MUSCIDJE) ; some form galls (CECIIJOMYIIDJE), some breed in fungi 

 (MYCETOPHYLID^E and PLATYPEZID^E) ; many are leaf-miners (many 

 ANTHOMYIN^E, most of the TRYPETIN^E, and some ORTALIN^E) ; 

 whilst the vast majority of the enormous family MUSCIDJE breed 

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

 other families, in fact this habitat might be considered the most 

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

 and CONOPID^E on Orthoptera and Hymenoptera ; the (EsTRiDyE 

 on Mammalia ; CYRTID^E (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 one 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 will be well for 

 him to start with the paramount impression that as much care 

 must be taken both in their capture and subsequent treatment as 

 would be required in the case of Microlepicloptera. The delicate 

 pubescence with which the majority of the species are covered is 

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

 BOMBYLIIU^E, THEREVID^:, 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 TIPTJLID^, MYCETOPHILIDJE, CULICID^, and CHIRONO- 

 MIDJE, amongst the NEMATOCERA, and theLEPTiD^, DOLICHOPIDJE, 

 Tachinids and Anthomyids amongst the BRACHICERA and CYCLO- 

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

 the least touch (in SEPSINJE 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 

 butterfly 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 fingers 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 



