58 



INSECTS. 



Sand-Flies, etc. 



COLUMBATSCH FLY 



(enlarged). 



The two families now to be mentioned have been termed the 

 anomalous, or fly -like Nematocera, since although their antennae are 



many-jointed, they are shorter than in the foregoing families, and their limbs and 



bodies instead of presenting the aspect of those of the gnats and midges, are shorter, 



thicker, and closely approach in this respect those of ordinary flies. To the family 



Simuliidce belong the minute " sand-flies " of the tropics, which surpass even the 



mosquitoes in their venomous bite, and on account of their minute size are far more 

 difficult to cope with. In these insects the mouth-parts are adapted 

 for piercing ; and the early stages of life are passed in water. The 

 best known European example is the Columbatsch fly (Simulia 

 columbatzensis), taking its name from a village in Servia, where 

 it is a great pest. In fact, in all the countries irrigated by the 

 lower waters of the Danube, this fly, hardly larger than a flea, 

 abounds ; and it is said that in Hungary cattle and sheep have 

 been destroyed by hundreds owing to the tortures they have 

 suffered from these insects. The little flies creep into the eyes, 



nose, and ears of their victims, and there gorge themselves with blood, driving the 



poor beasts to the verge of madness by the intolerable irritation of their bites. 



The second family of the group (Bibionidce) contains the well-known St. 



Mark's fly (Bibio marci), a large, black, hairy, slow-flying insect, common in spring, 



and taking its name from its being frequently seen in numbers on or about St. 



Mark's Day. The two sexes differ greatly in many respects, the male having the 



wings clear, whereas those of the female 



are dusky ; again the eyes in the male are 



so large that the entire head seems to be 



composed of them, but in the female these 



organs are small and wide apart. This 



distinction, however, although not usually 



in so pronounced a form, is observed 



between the two sexes of many flies. The 



eggs — in number amounting to about one 



hundred and fifty — are laid on the ground 



among vegetable or animal debris, on which 



the larvae subsequently feed. In the grub 



the head has neither eyes nor recognisable 



antennae, but the mouth-parts are distinct ; 



the body consisting of twelve segments, 



each of which is surmounted by a row of bristles. After passing the winter in the 



soil in an immature state, the larvae ascend to the surface in the spring, and take 



on the pupal stage, from which, after about a fortnight's time, the perfect insects 



emerge. 

 Horse-Fiies, or Although related to the gnats and midges by the nature of the 



Breeze-Flies. s ]^ through which the pupa makes its escape from the larval skin, 



and consequently referred to the section Orthorrhapha, the flies of this family 



approach those of the second section in the shortness of their antennae, and since 



all the Diptera with short antennae were formerly termed the Brachycera, — as 



ST. mark's fly (nat. size, with enlarged figure of 

 larva and pupa). 



