56 



PREVENTIVE MEASURES. 



It is doubtful if one fanner out of a thousand fully realizes the 

 daui^-er arisiuo- from volunteer wheat. This g-rowth springs up in the 

 fields in g-reater or less abundance, and is almost invariably left to 

 itself, as, having no value, it is thought not worth while to bother 

 with it. Besides, the general practice in many sections of the coun- 

 try of seeding the wheat lands to timothy and clover would prevent 

 any attempt to destroy the volunteer wheat, except by pasturing, 

 which is not considered a part of good husbandry at that season. A 

 rotation of crop, however, has in itself some advantages, as it forces 

 the flies to migrate from one field to another, in which there must be 

 more or less casualties, and many more would probabh" be attracted 

 to the grasses and the young fall wheat be protected to this extent 

 from attack. Where wheat is to follow wheat in the same field, it 

 will certainly pay the farmer to destroy this volunteer growth, as it 

 not onl}' harbors all of these flies and ofl'ers unusual advantages for 

 the development of this midsummer brood, but it offers a breeding 

 place for the Hessian fly as well. Volunteer wheat, then, should be 

 destroyed whei'ever possil)le by the plow or disk hai'row, and, where 

 practicable, by pasturing, so as to prevent the flies from breeding 

 therein. Burning over the grass lands, except timothy or clover, 

 where it is probal)!}^ not necessary, will ofl'er much protection, espe- 

 cially in spring-wheat growing regions, and where fall wheat is much 

 grown, reasonably late sowing will probably prove one of the most 

 efl'ective means of protection. 



NATURAL ENEMIES. 



While this species probably has its usual number of natural ene- 

 mies, it is not always possible to determine the exact species from 

 which these have been reared, but an insect that is parasitic on one 

 species of these flies might ])e confidentl}- looked for as being parasitic 

 upon other allied species. RJiys-salus oschiidls Ashm. is parasitic on 

 a species of Oscinis larvae mining in the leaves of plantain, in Wash- 

 ington, D. C. Aphsereta calif orn lea Ashm. and A. oscinldis Ashm. 

 have both been reared from other species of Oscinis, while I have 

 reared Cyrtogaater occideoitalis Ashm. from either this species, O. 

 soror^ or 0. ^anhrosa, in Indiana, though it is known to occur from 

 Texas to South Dakota and east to Virginia and the District of Colum- 

 bia. These are all minute four-winged flies, and there are probably 

 many other.^ that also help to keep these flies reduced in numbers. I 

 have also observed the common parasitic fungus EiytomoiylithoraniiiiHCse, 

 attacking the flies, but this is probably a minor factor among their 

 natural enemies. 



