A Monograph of Egyp tian Diptera. 13 



even on the earth in the sunlight. A few of them are injurious 

 in the larval stage such as Eumerus and Syritta, but on the other 

 hand many are very beneficial, being aphidiphagous (Syrphus, 

 Paragus, Sphaerophoria, etc.) ; some live in liquid filth and decay- 

 ing vegetable matter (Eristalis) and others live in the stems of 

 plants and in fungi. The larvae of some species inhabit the nests 

 of the large Hymenoptera such as Vespa and Bombus and they 

 probably act rather as scavengers than as parasites, while others 

 have been found in ants' nests. I do not agree with Verrall's sup- 

 position that "Eumerus in some way lives in the burrows of small 

 aculeate Hymenoptera" as both E. a morn us and E. vest it us, the 

 commonest Egyptian species, have been bred from various plants 

 such as onions, potatoes, water-melons, etc. It is probable thai 

 Verrall's supposition is derived from the curious habits of the 

 adults which mimic Hymenoptera in their flight and in the case 

 of one or two species can only be caught on the ground or among 

 low lying plants where nests of Hymenoptera may be in close 

 proximity. It is probable however that Eumerus found in such 

 localities are about to oviposit and are merely seeking a way to 

 the roots of the plants which their larvae inhabit. It is not 

 unlikely, therefore, that occasionally these insects may enter the 

 burrows of Hymenoptera or any other holes in the ground. 



The metamorphoses of most genera have been more or less stud- 

 ied. The larvae are rather various in appearance, and as remark- 

 ed above, their biology is at the same time very different, in spite 

 of this they have, however, some features in common. Lundbeck 

 says that "the dermis is always tough or more or less leathery, 

 "and it is shagreened from small spinules or hairs which are often 

 "divided into two to four corrugations. There are in all twelve 

 "segments, the head included. Above the mouth opening are two 

 "antennae-like organs; they are, or may be described as, two-jointed, 

 "the last joint bearing two papillae alongside ; these two papillae 

 "are not similar, one has at the end a small refractive body, while 

 "the other, the one nearest the mouth, is truncate and generally a 

 "little crenulated at the apical margin. These organs, which arc 

 "present and nearlv uniform in all cyclorrhaphous larvae, are 

 "generally termed antennae; Lowne takes them to be the maxillae. 

 "They have been studied by Wandolleck (Zool. Anz. 1898, 283) and 

 "this author concludes that the whole organ must be taken as an 

 "antenna, and this in spite of his observation, that the upper papilla 

 "with the refractive body gets its nerve from the upper pharyngeal 

 "ganglion, while the other papilla, which is nearer the mouth gets 

 "the nerve from the lower ganglion. De Meijere suggests in his 

 "work on the Lonchopt era-larva, (Zool. Jahrb. Abtheil. fur Syst., 

 "XIV, 1900, 100) after comparing the organ with the antennae and 



