i82 . INTRODUCTION 



numerous groups with a thick membranous proboscis and broad end-flaps, there 

 are forms with a long proboscis projecting far forwards and pointed end-flaps. 

 Muscidae of this sort are sometimes voracious blood-suckers, as for example 

 Stomoxys calcitrans ; others, such as the species of Scatophaga, which possess a 

 similar proboscis, live upon excrement, but also suck flowers and kill other insects. 

 The proboscis of flies is at least as complicated and eflScient an apparatus as the 

 suctorial tube of bees. Since the large majority of Muscidae possess a membranous, 

 more or less thick and long proboscis provided with broad end-flaps, and adapted 

 for feeding upon moist substances, whether of vegetable or animal nature, we can by 

 no means regard the family as mainly anthophilous. The more regular flower 

 visitors belong more or less exclusively to the following sub-families only: — Phasineae, 

 Ocypterineae, Gymnosomineae, Phanineae, Tachinineae, Dexineae, some Sarcophagineae 

 (Onesia, Sarcophaga), Muscineae (Graphomyia, Calliphora, Lucilia, Cyrtoneura), Ult- 

 dtneae (Ulidia), Anthomyiae (Aricia, Spilogaster, Anthomyia), Scatophagineae, Trypetineae 

 (Acidia, Trypeta, Urophora, Myopites, Oxyphera, Tephritis), Sepsineae, Chloropineae 

 (Chlorops), and some Drosophilimae; the visits to flowers that are paid by species 

 belonging to the remaining twenty sub-families are scarcely worth mentioning. 

 In the mouth-parts of individual flower-visiting species belonging to the great 

 family of Muscidae indications are found of increased specialization in the selection 

 of flowers (e. g. in Prosena, Myopites, Ensina, and some species of Tephritis), but 

 such cases are exceptional and by no means the rule. Taking the behaviour of the 

 Muscidae in general, it appears that ability to pollinate with correlated bodily 

 structure occurs quite irregularly in the individual sub-families, so that these insects 

 must be regarded as allotropous flower visitors. 



The same holds true for the Empidae (op. cit., p. 113), which in their mode of 

 life show a relationship to other predaceous flies {Asilidae, Therevidae, Lepiidae). 

 The proboscis is sometimes short, sometimes elongated. It projects horizontally 

 forwards^(Hybos), or is curved back (Rhamphomyia), or is directed perpendicularly 

 downwards (species of Empis). Species of Rhamphomyia and Empis appear 

 as visitors of flowers that only suck and do not eat pollen, and the males of species 

 of the latter genus suck nectar, while the females in addition feed by sucking 

 other flies. 



The bloodthirsty Tabanidae possess a thick proboscis, often extended forwards, 

 and distinguished from that of other blood-suckers by its broad end-flaps. In 

 Tabanus it is once more the males which specially devote themselves to sucking 

 flowers, while the females as a rule draw blood from horses and cattle. Here too 

 there are in addition to forms that are exclusively blood-suckers (Chrysops, and 

 others), individual genera (Silvius, Pangonia) of which the species (at least the males) 

 are exclusively anthophilous. 



The Conopidae only suck nectar. The proboscis may be of considerable length 

 (in Occemyia), enabling nectar-yielding Papilionaceae (such as Trifolium) to be 

 plundered. They confine themselves almost exclusively to flowers with completely 

 concealed nectar. As they suck while holding firmly with their feet, social flowers 

 are visited with marked preference. 



Although the ^zxaAy oi \^t Bee-flies {Bombyliidae) includes short- tongued forms 

 (Lomatia, Anthrax, Argyromoeba) with a decided preference for flowers with exposed 



