vii BLOOD-SUCKING FLIES 457 



ment : 1: Super-family Eremochaeta. for Stratiomyidae, Tabanidae, 

 Acanthomeridae and Leptidae ; 2. Tromoptera, for Xemestrinidae, 

 Arroceridae, Bombyliidae, Therevidae, and Scenopinidae ; 3. Ener- 

 gopoda, for Asilidae, Dolichopidae, Empidae and Lonchopteridae, 

 Phoridae being included with doubt ; 4. Mydaidae remains isolated. 



This classification is based on the relations of the eyes and 

 bristles of the upper surface, and on the powers of locomotion, 

 ai. : rial or terrestrial. At present it is not sufficiently precise to 

 be of use to any but the very advanced student. 



Blood-sucking Diptera. The habit of blood-sucking from 

 Vertebrates is, among Insects, of course confined to those with 

 suctorial mouth, and is exhibited by various Diptera. It is, 

 however, indulged in by but a small number of species, and 

 these do not belong to any special division of the Order. It is 

 remarkable that as a rule the habit is confined to the female sex, 

 and that a large proportion of the species have aquatic larvae. 

 This subject has many points of interest, but does not appear to 

 have yet received the attention it merits. We give below a 

 brief summary of the facts as to blood-sucking Diptera. 



Series I. Nemocera. In this section the habit occurs in no less 

 than five families, viz. : 



Blepharoceridae. Cunqnra ; in the female only ; larva aquatic. 



Culicidae. Culex, Mosquitoes ; in the female only ; other 

 genera, with one or two exceptions, do not suck blood ; 

 larvae aquatic. 



Chironomidae. Ceratopogon, Midge ; in the female only ; ex- 

 ceptional even in the genus, though the habit is said to 

 exist in one or two less known, allied genera; larval habits 

 not certain ; often aquatic; in C. Mpunctatus the larva lives 

 under moist bark. 



Psychodidae. P/ilebotomus : in the female only (?) ; quite ex- 

 ceptional in the family ; larva aquatic or in liquid filth. 



Simuliidae. Sim i/lium, sand-flies; general in the family (?), 



which, however, is a very small one ; larva aquatic, food 



probably mixed vegetable and animal microscopic organisms. 



Series II. Brachycera. Tabanidae. Gad-flies : apparently general 



in the females of this family ; the habits of the exotic forms 



but little known ; in the larval state, scarcely at all known ; 



some are aquatic. 



