47 DIPTERA CHAP. 



iii habits, but the great majority are terrestrial, frequenting 

 trees, etc. The former larvae are very slender, and move after 

 the manner of leeches ; they give rise to imagos with naked 

 wings, while the terrestrial larvae produce flies with hairy 

 wings. There are also important distinctions in the pupae of 

 the two kinds ; the correlation between the habits, and the dis- 

 tinctions above referred to, is, however, far from being absolutely 

 constant. 1 Certain species of midges are in this country amongst 

 the most annoying of Insects ; being of very minute size, scarcely 

 visible, they settle on the exposed parts of the body in great 

 numbers, and by sucking blood create an intolerable irritation. 

 Ceratopogon varius is one of the most persistent of these annoyers 

 in Scotland, where this form of pest is much worse than it is in 

 England ; in Cambridgeshire, according to Mr. G. H. Yerrall, 

 the two troublesome midges are the females of 0. pulicaris and 



('. biji/'tlcff'ft(S. 



Fam. 6. Orphnephilidae. Small, brown or yellowish, flies, 

 bare of pubescence, with very large eyes contiguous in both sexes, 

 and with antennae composed of two joints and a terminal bristle ; 

 both the second joint and the bristle are, however, really compl< .' . 

 One of the smallest and least known of the families of Diptera, 

 and said to be one of the most difficult to classify. The nervures 

 of the wings are very distinct. Nothing is known of the habits 

 and metamorphoses ; there is only one genus Orplineph il ; it 

 is widely distributed ; w r e have one species in Britain. 



Fam. 7. Psychodidae (Moth-flies}. Extremely small, helpless 

 flics, -usually with thickish antennae, bearing much hair, with 

 wings broader than is usual in small flies, and also densely clothed 

 with hair, giving rise to a pattern more or less vague. These 

 flies are very fragile creatures, and are probably numerous in 

 species. In Britain forty or fifty species have been recognised. 2 

 A South European form is a blood-sucker, and has received the 

 appropriate name of Phlebotomus. The life-history of Pericoma 

 canescens ha recently been studied by Professor Miall. 3 The 

 larva is of aquatic habits, but is amphibious, being capable of 

 existing in the air ; it has a pair of anterior spiracles, by means 



1 For metamorphoses of aquatic species of Ceratopogon, see Miall and Memert, 

 already quoted : for examples of the terrestrial species, and their illustrations, 

 refer to Mik, ll'icn. ent. Zcit. vii. 1888, p. 183. 



- Monograph, Eaton, Ent. May. xxix. and xxx. 1893, 1894 : supplement op. cit. 

 1896, etc. s Tr. ent. Soc. London, 1895, p. 141. 



