December, '16] hungerforD: sciara maggots injurious 547 



However, Sciara maggots and adults are the hosts of a few forms. 

 W. 11. Thompson (19) gives an article "Sur un diptere Parasite de la 

 larve d'un mycetophilidie. " He found some Sciara maggots infested 

 with parasites which he argues must be larvae of a "Dexiid" or more 

 probably of a "Tachinid." 



In one series of experiments we had a number of three-inch pots of 

 geraniums containing some dried blood fertilizer which were being used 

 as a trap pot in a place where the flies were abundant. One pot sat 

 in the corner of the infested bed and here a small nymph of an assassin 

 bug (Milyas) took its abode, with the result that during the nineteen 

 days of its presence there, it quite effectively kept the pot free from 

 eggs. 



In our study of the development of the eggs, we were at one time 

 troubled by the predatory tendencies of a small mite which unfortu- 

 nately we did not preserve for identification. 



These same mites were seen to attack living flies, the wings of which 

 held them captive to the moist glass. 



There is, however one parasite, a nematode, that most eff].ciently 

 reduced my stock of flies to the vanishing point just recently. It 

 works within the maggot and reaches maturity there. Though the 

 parasite occupies most of the space within the maggot, the latter is 

 sometimes permitted to become an adult, minus, however, all traces 

 of its organs of reproduction. Plate 41, figure 7, shows an adult female 

 parasite. The life-history of this nematode and its effect upon the 

 host will appear in another publication. ^ 



Summary 



The life-history of Sciara coprophila requires a period of from twenty- 

 four to thirty-two days. The egg stage occupies six days, the maggot 

 stage twelve to fourteen days, or longer, the pupa stage six days and 

 the adults have lived under laboratory conditions about a week. The 

 maggots, though omniverous feeders, are injurious to potted plants 

 through their feeding upon the roots and root hairs. 



Soils that are moist and rich in manure or dried blood attract the 

 the flies and lead to the laying of large numbers of eggs in these favored 

 situations, the result being that plants growing in soils of this charac- 

 ter are seriously damaged. 



The maggots, though resistant to most insecticides, quite readily 

 succumb to drying. Thus, by letting the soils dry out occasionally, 

 little trouble will be experienced. Where a serious infestation occurs, 

 a judicious drying out of the soils, use of dry sand on top of the dirt, 

 and trap pots of dried blood and earth and sprouting grain used to 

 attract egg-laying, will effectually control the pest. The maggots 



^See also Bezzi (2) for others. 



