DIPTERA. 43 



of a year is something fearful. Only a few days after the pupae in a 

 bucket are transformed into gnats, eggs which have been left by the 

 females may be observed on the surface of the water in little clusters. 



Many species of gnats, known as mosquitoes, are to be found in 

 America. All travellers speak of the sufferings endured by a stranger 

 in that country from the bites of these insects. One can only 

 preserve oneself from these cruel enemies during sleep by hanging 

 gauze, called a mosquito curtain, round the bed. Mosquito curtains 

 are not only necessary in America ; during the hot season, in Spain, 

 throughout the whole of Italy, and a part of the south of France, it 

 is necessary to hang these curtains round the bed, if one wishes to 

 obtain any sleep ; it is also a necessary precaution not to have a light 

 in one's bedchamber, as the sight of it at once attracts these 

 dangerous companions, whose buzzing and stinging prevent any 

 possibility of repose during the whole night. Such is our advice to 

 people who travel in the above-mentioned countries. 



The TipiiUdcE have a narrow, elongated abdomen, and long and 

 slight limbs. The head is round, and the eyes, which are compound, 

 are, especially in the males, very large. The wings, which are long 

 and narrow, are sometimes held wide apart, sometimes horizontally, 

 and sometimes bent so as to form, as it were, a roof The balancers 

 are naked and elongated ; the abdomen long, cylindrical, and often 

 terminating in a club in the male, and in a point in the female. The 

 antennae, which are longer than the head, are generally composed of 

 from fourteen to sixteen joints, and are sometimes in the form of a 

 comb or saw, sometimes furnished with hair, in form of plumes, 

 'bunches, or in a whorl. The larvae live on plants, in the fields, in 

 gardens, and sometimes in woods. The perfect insects, at first sight, 

 _|resemble gnats, but are without a trunk, or rather their trunk is 

 extremely short, terminating in two large lips, and the sucker is 

 composed of two fibres only."' The larger species of Tipdce, which 



* The genus Cecidomyia, which belongs to this family, presents the most 

 extraordinary instance of agamo-genesis — or reproduction without fertihsation by 

 another individual — at present known among insects. Until lately it was almost 

 an axiom with naturalists that no insect was capable of reproduction until it had 

 attained its adult or perfect state. Several Continental observers, some of them 

 without any knowledge of the others' discoveries, have found that the larvcc of 

 some of the species of this genus reproduce larvte resembling themselves in every 

 respect ; and what is still more strange, these larvce live in a free state within the 

 parent larvae, feeding upon its tissues, and causing its ultimate destruction. 



A very interesting article on this subject will be found in the Popular Science 

 Review for the ist April, 1868. The larvse of a species {Cecidomyia tritici) 

 frequently causes much injury to the wheat. — Ed. 



