BULLETIN No. 200, 



THE MYCETOPHILIDAE OF NORTH AMERICA. 



Part IV (Conci^usion)*. 



O. A. JOHANNSEN. 



The species of the genera belonging to Series I as weh as 

 the first 6 genera of Series II of the subfamily Mycefophilinae 

 were described in Part III. In this paper the species of the 

 remaining genera are characterized, as well as those of the sub- 

 family Sciarinae. The members of the former so far as known 

 injure mushrooms only; the latter constitute the most important 

 gi'oup so far as the agriculturist is concerned. 



Though occasionally reported as injuring" mushrooms the 

 members of the Sciarinae are not as a rule regarded as serious 

 pests of the fleshy fungi, differing in this respect from the 

 species of the other subfamilies. After partial decay of fun- 

 gous growths, however, larvse of Sciara are found in abund- 

 ance, and it is this f>act, which in some cases at least, has led 

 observers and growers to attribute the destruciion to these 

 gnats when in all probability the injury was caused by species 

 of Mycetophila, Bxechia or Phorids. 



On the other hand there is no lack of evidence of the harm- 

 ful character of some species of Sciarinae to seed corn, to pota- 

 toes, to wheat, and to the roots of other plants. Professor 

 Forbes in his 7th report refers to the injury which the larvae 

 do to seed corn, and in his 15th (pp. 95-98) notes the destruc- 

 tion of cucumber plants by these pests. In an earlier report he 

 mentions the occurrence of larvae infesting the roots of grass. 



* Papers from the Maine Agricultural Experiment Station, Entomol- 

 ogy No. 52. Parts I, II and III were published in Bulletins 172, 180 

 and ig6 respectively. 



