46 



Most Diptera lay eggs, but a few produce living larvae, and are then called Viviparous, 

 in contradistinction to the egg layers, which are termed Oviparous. Some few species 

 also retain the larvae in the interior of their body until they have reached the pupal state,, 

 and then discharge them in that condition — these are called Pupiparous. 



One of the most noticeable features of this great family of insects is their very great 

 profusion, and the large number of species they embrace. In all parts of the world, and 

 at almost all seasons of the year, they seem to furnish an inexhaustible supply. The 

 numerous class of insectivorous birds depend largely on them for their subsistence. 



Another, and most important duty they fulfil is that of acting as part of nature's 

 great army of scavengers, and removing the innumerable quantities of decaying animal 

 and vegetable matter that are to be found on every hand. Indeed were it not for the 

 great assistance thus rendered by hosts of insects, acting in many cases invisibly to us, 

 it is doubtful if human life could be sustained with any degree of health or comfort. 



In this great work, assigned by a beneficent Creator to the insect world, the Diptera 

 or flies play a most important part ; their enormous fecundity and their marvellous rapid- 

 ity of generation adapting them specially for this work. 



On the other hand there is no doubt that much annoyance and irritation are caused 

 both to man and beast by the attacks of flies. With the sonorous boom of the mosquito 

 sounding in our sleepless ears, it is difficult to philosophise calmly on the operations of 

 this blood-thirsty insect, and to believe that there may be even a remote possibility that 

 the attacks of this persistent and persevering fly may be conducive to our health. 



To what a world, too, of untold misery is that unhappy animal subjected in the sea- 

 son of " fly -time," who, like Burns' " Maggie " of poetic fame, possesses " scarce a stump" 

 to defend itself agaiust the persecution of its irritating tormentors. 



There have been trying occasions, we strongly suspect, when some of us would have 

 been only too glad to have been able to have afforded proof to demonstration that Lord 

 Monboddo's celebrated caudal theory was founded on fact, and that our personal comfort, 

 as well as our landed possessions, would have been greatly enhanced by an actual and verit- 

 able enjoyment of an " estate in tail." 



According to the late Prof. H. Loew, all Diptera have been for many years past 

 divided into two large sections — Nemocera and Brachycera. 



The first section of Nemocera, or thread-horned Diptera, have antennae with more 

 than six joints, and the palpi with either four or five joints. The second section of Brachycera y 

 or short-jointed Diptera, have not more than three distinct joints of the antennae, and the 

 palpi have not more than two joints, and often only one. 



This section embraces by far the largest number of species. 



Section I. — Nemoceile. 



In this are comprised those comprehensive families known popularly as Gnats or 

 Mosquitoes, and Daddy-long-legs, or the Culicidce and Tipulidce, to use scientific names. 

 Our well known acquaintance, the Mosquito — known unfortunately to most of us by 

 painful experience— will stand 

 as a representative of a very 

 large and interesting family 

 who are found in every part 

 of the world — both in artic 

 and tropical regions as well 

 as in more moderate climes. 

 Loew's catalogue of N. A. 

 species comprises a list of 32. 

 Figure 17 represents a fe- 

 male Mosquito, Culex pipiens 

 Linn ; the males are harm- 

 less, leaving all the biting to 

 their more irritating wives. Fig- 18 - 



Fig. 18 shows the mouth parts of the female, and the formidable lancet she employs 



