VII BLOOD-SUCKING FLIES 457 



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

 Acauthomeridae and Leptidae ; 2. Tromoptera, for Neiuestriuidae, 

 Acroceridae, Bombyliidae, There vidae, 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, 

 aerial or terrestrial. At present it is not sufticiently precise to 

 be of use to any l:)ut 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, indvilged 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, Ijut 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. Curupira ; 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. Ceratoyogon, 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. hipimctcUus the larva lives 

 under moist bark. 



Psychodidae. Phlchotomus : in the female only (?) ; quite ex- 

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



Simuliidae. Simulium, 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. 



