﻿136 Journal New York Ent. Soc. [Voi. in. 



The larvK of Blepharoceridse live in swift running water like those 

 of Simuliiim, or in still swifter water. The mouth parts of the adults 

 seem to be capable of biting. 



Rhyphus, and some Bibionidre, have biting mouth parts. 



Going now to the Brachycera, we find that Leptis and Atherix, 

 probably also other Leptid^, posses biting mouth parts capable of suck- 

 ing blood, but Symphoromyia is the only Leptid genus which has so far 

 been recorded to practice this habit. I have observed its blood-sucking 

 habit on San Francisco Mt., in Arizona. 



Thereva has biting mouth parts much like a Tabanid. Its larvae 

 live in slimy mud or moist earth. Other Therevidce have similar mouth 

 parts, but no species are known to suck mammalian blood. The larvae 

 in general are said to live in fungi and decaying wood, and the adults 

 to prey on other insects. 



In this connection it will be well also to mention the mouth parts 

 of the Asilidae, which are fitted for piercing and sucking, but which are 

 very different from those of the Tabanidte. They are specially fitted 

 for piercing the exoskeleton of insects, and differ strongly from the 

 mouth parts of genera which pierce the skin of mammals. 



To sum up, we have the following genera which are known to have 

 aquatic larvae and blood-sucking adult females :* Shiulium, Megarrhina, 

 Cuiex, Anopheles, Ceratopogon, Phlebotomiis (probably), and many 

 Tabanidffi genera. This list will doubtless in time be increased, as we 

 have blood-sucking genera, of which the larval habits are unknown ; 

 and genera whose larvae are known to live in water, but whose adults, 

 while possessing mouth parts capable of biting, have never been ob- 

 served to suck blood. 



On the whole the rule seems to hold good in the Nemocera, nearly 

 as good in the Brachycera, and not at all in the Cyclorhapha. The 

 Muscid genera seem to offer a marked contrast. In other words it is in 

 the oldest families that this correlation of habit obtains. These families 

 doubtless originally sucked the plants (Culicidae, Chironomidae Simu- 

 lidae, etc.), as has recently been suggested by Ficalbi, an Italian ob- 

 server. The explanation of these facts is left to the future student. 

 Why should this more or less complete correlation of habit exist in the 

 older families of diptera ? 



* I am aware that males of Ciilex have been recorded as sucking blood. — C. 

 H. T. T. 



