BULLETIN No. 200. 



THE .AIYCETOPHILIDAE OF NORTH AMERICA. 

 Part lY (Conclusion)*. 



O. A. JOHANNSEN. 



The species of the genera belonging to Series I as well ai 

 the first 6 genera of Series H of the subfamily Mycetoplulina^ 

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

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

 family Sciai'iiiac. The members of the former so far as known 

 injure mushrooms only; the latter constitute the most important 

 group so far as the agriculturist is concerned. 



Though occasionally reported as injuring mushrooms the 

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

 pests of the flleshy 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 fact, wdiich in some cases at least, has led 

 observers and growers to attribute the destrucrion to these 

 gnats wdien in all probability the injury was caused by species 

 of Mycetophila, Bxecliia or Phorlds. 



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 larvse 

 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 larv?e 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 196 respectively. 



