BY FREDERICK A. A, SKUSE. 23 



Order DIPTERA. 



Wings two ; mesothoracic, membranous, with radiate veins ; 

 posterior wings wanting, represented by a pair of small clavate 

 filaments called halteres; mouth suctorial ; metamorphosis perfect; 

 larva apodal ; pupa inactive. 



Section I. ORTHORHAPHA.. 

 The pupa case opening longitudinally. 



Division I. Nematocera. 



The flies belonging to this division are characterised by the 

 possession of long thread-like antennai consisting of several joints, 

 in many instances beautifully ornamented with whorls of long 

 delicate hairs, especially in the males ; nearly all are to be recog- 

 nised without much ditiiculty by their long slender body and limbs, 

 small rounded head, and elevated thorax ; and as typical examples 

 might be mentioned the familiar Mosquitoes (Culicidai) whose 

 blood-sucking propensities are only too well-known, the Daddy- 

 longlegs (Tipulidte), and the swarms of Midges (Chironomidse, 

 Cecidomyidac, ikc). They are to be found especially in damp and 

 shady situations, and are to be met with abundantly in all regions 

 presenting these essential conditions of their existence; but there 

 is, nevertheless, in these insects, a considerable variety both of 

 character and habits; these latter will be fully considered as we 

 come to deal with each family separately in future papers, though 

 it will be well to here give a preliminary sketch of them. 



The Nkm.^tocera, formerly regarded as divisible into only two 

 families, is now split up into thirteen. 



Fam. 1. — CECiDOMViD.K (Gall Midges). Characters: Small deli- 

 c&U^ Hi)ecies ; antenna; long, necklace-like; often no ocelli ; legs 

 very long, slender; coxie short; tibias slender, without spurs; 

 wings well hain^d, with very few veins. 



