718 Charles Paul Alexander 



worms (Patterson, 1908) and other soft-bodied animals. Dissections of 

 Trpula abdmninalis show the food of this species to consist principally of 

 small filamentous algae, diatoms (Diatoma, Navicula, and others), and 

 rootlets of small plants. The alimentary tract is often crammed with 

 sand or soil particles. The species of Tipula and Nephrotoma that are 

 injurious to plants, considered later in this paper under the heading 

 Economic Importance, effect their damage by devouring the living tissues 

 of the roots. The Cylindrotominae feed on the living tissues of the plants 

 on which they dwell; in the case of Phalacrocera, Triogma, and Liogma 

 these are mosses, in Cylindrotoma they are the parenchyma and epi- 

 dermis of higher plants (spermatophytes) . With this habit of feeding 

 on plant tissues the extreme of sluggishness of motion is attained. The 

 wood-l^oring species of Tipulinae (such as the species of Tanyptera and 

 Ctenophora) feed on the ligneous tissue of the trees in which they occur. 

 Other species of crane-flies injure young seedUngs by destroying the bark 

 and the bast tissues. 



The hexatomine and pediciine forms represent the opposite extreme, 

 being for the most part carnivorous or even cannibalistic in their habits. 

 In order to capture their prey they are of necessity rapid of movement, 

 and in this group the most graceful and active of all tipulid larvae are 

 found. The motions of the species are, at times, exceedingly agile and 

 snakelike. The food consists of a variety of animal forms. Dicranota 

 has been recorded as feeding on worms of the genus Tubifex, Pedicia 

 usually feeds on the larvae of small insects, especially Chironomidae, 

 but the large species of this genus and of Eriocera are capable of capturing 

 almost any insect of a size equal to their own. The larvae of Eriocera 

 spinosa are able to inflict painful bites on tender parts of the skin of a man. 

 Penthoptera, Eriocera, Hexatoma, and most of the limnophiline groups 

 likewise feed largely on midge larvae. From one small larva of Limno- 

 phila (Dicranophragma) fuscovaria the writer has dissected out the remains 

 of two large midge larvae, whose heads were nearly half the size of that of 

 the captor. The chitinized mentum in these predacious forms is very 

 weak or is lacking, allowing for a tremendous distension of the gular region. 

 The mandibles are always developed into powerful curved hooks which 

 serve well their purpose of grasping and holding the victims. The 

 esophageal region is often retrorsely roughened to prevent the egress of 

 anything that has once started down the throat. In addition to the 



