THE SPIKE-HORNED LEAF-MINER. 15 



and oviposition consisted of a lantern chimney covered with cheese- 

 cloth and placed over a small potted plant (PL II, fig. 6). A lump 

 of sugar moistened with water was placed in the bottom of the cage. 

 The senior author in his study of the oviposition and feeding habits 

 used a cage consisting of a small lantern chimney placed in an earthen 

 saucer. Inside of the lantern chimney was placed a bottle containing 

 a small millet plant in water; these plants were afterward potted. 

 Moistened sugar was also placed in this cage. It was found that 

 adults in the small cages lived for a longer period than in the larger 

 rearing cages, probably on account of having access more readily to 

 food given them. 



PARASITIC ENEMIES. 



The important natural enemies of this leaf-miner are parasitic 

 Hymenoptera, of which the species named below have been reared. 

 Some of these have been reared at widely separated localities and 

 from their host working upon different food plants. These para- 

 sites become active in early spring, increasing in abundance with 

 each succeeding generation, until their activity is retarded by the 

 approach of cold weather. 



It may be possible that the almost total disappearance of the host 

 during midsummer in some localities is due to the effective work of 

 some of these parasites, the life histories of which have not been 

 worked out. 



Cirrospilus flavoviridis Cwfd. — This species was reared from a 

 mine of C. dorsalis in a timothy leaf taken at Ely, Nev., by C. N". 

 Ainslie. It is also a parasite of the leaf-miners Agromyza pusilla 

 Meig. and A. parvicomis. 



Cyrtog aster occidentalis Ashm. — This species was reared by the 

 junior author, on May 9, 11, and 18, 1914, from puparia of C. dor- 

 salis, taken from barley leaves at Yuma, Ariz., and again on June 3, 

 1914, from a puparium which was removed from a leaf of wheat 

 taken at Tulare, Cal. During 1913 the senior author reared it 

 from C. dorsalis mines in corn at Columbia, S. C. G. G. Ainslie 

 reared it on May 11, 1914, from C . dorsalis mines in corn at Lake- 

 land, Fla., and H. E. Smith reared it May 25, 1914. from mines of 

 this species in corn at Greenwood, Miss. 



Diaulinus websteri Cwfd. — This parasite was reared in December, 

 1914, by E. L. Barrett from larvae of C. dorsalis working in barley 

 at Pasadena, Cal. The species was described by Crawford 1 (p. 184) 

 from specimens recorded from Tempe, Ariz., under Webster No. 7286. 



Diaulinopsis callichroma Cwfd. — This species was also reared 

 from G. dorsalis larvae working in corn, first by G. G. Ainslie at 



1 Crawford, J. C. Descriptions of new Hymenoptera. In Proc. U. S. Nat. Mus., v. 43, 

 p. 163-188. 1912. 



