798 



AN INTRODUCTION TO ENTOMOLOGY 



Fig. 1007. 



They feed on over-ripe fniit, the exuding sap of trees, and upon the 

 nectar of flowers. Figure 1006 represents the venation of the wings 

 and Figure 1007 the form of the antennas. Only four 

 species of this genus are recorded from the United 

 States. 



The larva: are found in decaying vegetable matter, 

 in manure, in sewage, and in similar material. 



Trichocera.— The members of this genus often at- 

 tract attention by appearing in swarms in the autimm 

 and early spring, and sometimes on warm, sunny daj^s 

 in winter. The swarms vary greatly in size, sometimes 

 one includes thousands of individuals. They are usually 

 from five to twenty-five feet above ground; and all members of a 

 swarm face the wind. 



. These flies are often found during the winter months in cellars, 

 resting on the windows. . Nine species have been described from our 

 fauna. In this genus the radial sector is three-branched and there 

 are two distinct anal veins. 



The larvae are found in decaying vegetable matter, beneath dead 

 or decaying leaves, and in fungi. They have also been found in 

 stored roots and tubers, especially potatoes. 



Mycetdhia. — A single species of these genus, M. divergens is found 

 in North America. This is a small fly measuring from three to four 

 millimeters in length and resembling superficially a fungus-gnat more 

 than a crane-fly. For this reason it has been commonly classed in 

 the Mycetophilidae. In this genus cell ist M2 is lacking, the radial 

 sector and media are each two-branched, and there is only one distinct 

 anal vein. 



The larvae are common in wounds on trees from which sap is 

 exuding, and in decaying wood. 



Family TIPULID^ 



The Typical Crane-Flies 



To this family belong the far greater number of the 

 crane-flies, the other three families of the Tipuloidea 

 including but few species. The typical crane-flies differ 

 from the Anisopidee in having a V-shaped transverse 

 mesonotal suture (Fig. 1008), from the Tanyderidas in 

 that the radial sector has less than four branches, and 

 from the Ptychopteridas in having two distinct anal 

 veins. 



Figure 1009 represents the venation of a wing of a 

 member of this family. The most striking feature of 

 this venation is the fact that the forking of the 



branched veins is near the distal end of the wing. This gives the 



wing a very distinctive appearance. 



Crane-flies are seen most often in damp localities, especially where 



there is a rank growth of vegetation; but sometimes they occur in 



Fig. 1008. — 

 Thorax of 

 a crane-fly 

 showin g 

 the V - 

 shaped su- 

 ture. 



