540 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 9 



Dr. Johannsen, in his excellent work on the Fungus Gnats of North 

 America, gives the description of forty-nine species in the geilus 

 Sciara, thirty of which are new species described by him, and four are 

 not assigned. A few others are named, the descriptions of which are 

 inadequate. Of these forty-nine species, rearing notes are given for 

 less than a dozen. S. 7nuUiseta Felt, agraria Felt and coprophila Lint- 

 ner were taken from mushroom cellars ; S. fulvicauda Felt and lugens 

 Joh. from decaying roots and wood; S. pauciseta Felt from decaying 

 potatoes; S. Hartii Joh. and cucumeris Joh. from cucumbers, while S. 

 tritici Coq. larvae are reported as feeding in wheat, and S. sativce. Joh. 

 was supposed to prey upon puparia of the Hessian fly. 

 , In the species we have studied we have often seen the larvge, es- 

 pecially the young ones, feeding upon the dead bodies of adults and 

 pupse of their own kind, but we have not observed them devour the 

 living. 



Habits and Economic Importance 



The family Mycetophilidse, to which these flies belong, gets its name 

 from the fact that many of them breed in fungi. The food of the 

 maggots of most species consists of either fungi or decomposing organic 

 matter. However, those of some species of the genus Sciara do, on 

 occasion, feed upon living roots of plants. C. A. Hart^ reports an 

 experiment to determine the food preferences of the larvae as follows : 



A cucumber plant was potted in clear sand and one hundred of the maggots were 

 placed about its base. These affected the plant, the stem evidently being eaten by 

 them. The same experiment was made with the addition, at one side of the pot, of 

 a cubic inch of decayed horse manm-e, such as is mixed with earth in growing cucum- 

 bers. The larvse were subsequently found collected about the piece of manure and 

 the plant remained uninjm-ed. Next, a plant was potted in a mixtm-e of manure 

 with earth from the forcing bed infested by maggots. The plant was not injured. 



His conclusions are that injury to living plants results only where 

 larvae are excessively abundant. He further states that: 



In no case were the maggots found attacking a firm, healthy stalk or root of the 

 cucumber plants, but at the least appearance of decay they attacked it in great 

 numbers, gnawing the surface and tunneling through it in all directions. 



It was our belief that such would be the case with those species we 

 have studied. But, during the past five years, under all sorts of soils 

 and conditions brought to bear in the flat glass root cages, we must 

 state that it has been our observations that they will attack healthy 

 roots even in pure, well rotted manure and in soils with the optimum 

 amount of dried blood fertilizer. We have frequently watched them 



1 Experiment by Mr. Green recorded in 26th Report of State Entomologist of 

 Illinois. 



