THE MIDGES. 77 



blood to flow faster, is the chief cause of the subsequent irritation." The insect, when undisturbed, 

 will gorge itself with blood until the abdomen is considerably distended. 



The habits of all the insects of this family are so nearly alike that the above description, which 

 applies specially to the common English species, will serve pretty well for them all. Of the typical 

 genus Gulex there are about nine British species, the commonest of which are the House Gnat 

 (C. ciliaris) and the Ring-footed Gnat (C. annulatuti), both of which frequent houses. The latter is 

 rather the larger, and appears to produce a greater amount of irritation by its bite. The Wood Gnat 

 (C. nemorosus) frequents woods and does not come into houses. Culex pipiens, with which the 

 commonest British Gnat was formerly identified, is especially an inhabitant of Northern Europe. 

 It was originally described by Linnaeus from Lapland, where it abounds in company with other 

 species, some of which occur in Great Britain. Its bite is said to be extremely irritating. The term 

 Mosquito, signifying merely a little fly, is applied in many places to other biting insects than 

 the Culicidae, but the insects against which travellers have generally to take precautions belong to 

 the present family. Many species have been described from different parts of the world. 



FAMILY II.- 



The remainder of the insects forming the first tribe of Diptera, which are frequently united into 

 a single great family, differ from the Gnats in the structure of the proboscis, which is short and fleshy, 

 and has the extremity generally furnished with a pair of fleshy lips, whilst the internal organs are 

 generally reduced in number, or more or less amalgamated with each other and with the proboscis. 

 The eyes are generally rounded or more or less oval, and the ocelli, with very few exceptions, are 

 deficient as in the Culicidae. 



The CHIBONOMIDJE, which we place as the first family of this group, are more or less Gnat-like 

 insects, with slender antennae considerably longer than the head, very strongly feathered, especially in 

 the males, in which they usually form two triangular bushes projecting from the front of the head. 

 In the males these organs usually consist of thirteen joints ; the females have a smaller number of 

 joints, and their antennae are usually shorter. The eyes are lunate, and there are no ocelli ; the legs 

 are very long and slender, and the tibiae are not armed with spines ; the veins in the wings closely 

 resemble those of the Gnats. 



Many of these insects are so Gnat-like that they are very commonly termed Gnats. They 

 resemble the members of the preceding family also in many of their habits, especially in having the 

 larvae and pupae aquatic, and in the custom of collecting in great swarms and dancing in the air. 

 They do not, however, in general possess the formidable offensive weapons of the Gnats, and most of 

 them are quite harmless. The best English name for them is that of Midges. 



The nearest approach to the true Gnat is made by the genus Corethra, one species of which 

 (C. plumicornis) is very generally distributed in Britain. It is a small insect, about a quarter of an 

 inch long, of a brown colour, with the antennae paler and banded with brown, and the feathery hairs of 

 the male antennae entirely pale ; two bands on the sides of the thorax, and the halteres are white. The 

 larva of this species, which may be met with almost every- 

 where in standing waters, is so beautifully transparent that it 

 can hardly be distinguished from the water in which it swims. 

 It is long and slender, with the thoracic region considerably 

 enlarged ; at the extremity of the body there is a delicate fan 

 of hairs which appears to have a respiratory function. The 

 pupa much resembles that of the Gnat, but is straighter, and 

 has the respiratory appendages of the thorax pointed. 



The genus Ckironomns, which gives its name to the ^ / % \ ^ P 

 family, includes an immense number of species ; one hundred CHIIIOXOMUS PLUMOSUS. 



and ninety-five are recorded by Mr. Walker as inhabitants of A. head magnified, shmvine tho antennae, tin- proboscis 



T> -. Vr<i -I <r), and the palpi <p). 



.Britain. Ihe commonest of all is C/nronomus plumosiis, a 



larger insect than the preceding, measuring from one-third to half an inch in length, of a pale 

 brownish-yellow colour, with three blackish stripes on the thorax, the palpi and antennae black, and 

 the abdomen blackish-grey, with a white band on the hind margin of each segment. The larva, which 



