June, '14] KELLY: BIOLOGY OF DIPLAZON 295 



Sept., 1913, with a legend underneath, stating that it was parasitic on 

 Syrphids, no mention of it being made in the text. 



In Kirchner's catalog of Hymenoptera, page 84, is recorded a note by 

 Herr Tischkin that he reared Diplazon kvtatorius from the larvse of 

 Adimonia rustica (a small Chrysomelid). In Ann. Ent. Soc. France 

 for 1877, page 408, Giraud and Laboulbene record rearing Diplazon 

 {Bassus) ia'tatorius from Syrphus halteatus. 



Dr. F. H. Chittenden notes in circular 43, second edition, page 5: 

 ''The efficiency of the Syrphus flies is greatly impaired by the presence 

 of a Braconid parasite (Diplazon latatorius) which is sometimes very 

 prevalent, almost exterminating its host in many fields." Doctor 

 Chittenden told the writer that the species had occurred to him to be 

 one of the very commonest inseots and had thus escaped being pub- 

 lished by him. 



This species was reared from puparium of Allograpta obliqua, the 

 larvse of which were collected by Prof. F. M. Webster at Clymers 

 Ind., May 17, 1886, and sent to Washington, and the same observer 

 also reared Diplazon sycophanta from Syrphid puparia at Battleground, 

 Ind., in 1889. It has been reared from Syrphid puparia on several 

 occasions during recent years by members of the Bureau of Entomol- 

 ogy, United States Department of Agriculture. Mr. V. L. Wilder- 

 muth reared adults from puparia at Yuma, Ariz. In a note on this 

 species he mentions collecting three Syrphid larvse, on April 23, 1912, 

 feeding on Aphis maidis. They pupated April 24, 26 and 27, from 

 these puparia -adult Diplazon Ia'tatorius issued on May 7, 9 and 12. 

 Mr. H. 0. Marsh reared adults from puparia of Syrphus sp. at 

 Garden Grove, Calif., from Allograpta fracta and Eupeodes volucris at 

 Brownsville, Tex. Mr. A. Willis reared adults from puparia of Syrphus 

 americanus at Ottawa, Kan., and the writer has reared adults from 

 puparia of Baccha clavata, Mesoyramma polita and Syrphus americanus 

 at Wellington, Kan. Messrs. Marsh and Smyth noted adults 

 swarming about cabbage heavily infested wuth Aphis brassicce at 

 Brownsville, Tex. 



On 14th of May, 1909, the writer, to bis great surprise, observed 

 the adult female of Diplazon latatorius ovipositing in eggs of Baccha 

 clavata. He never had supposed it possible that an Ichneumon would 

 lay its egg in the egg of another insect, and especially in this instance, 

 for the adult Diplazon measures 8 mm. in length, and the Syrphid egg 

 not more than 1 mm. The Diplazon female crawls astride the Syrphid 

 egg and thrusts her ovipositor in the egg in a similar manner to that 

 of Aphidius testaceipes which is figured in U. S. Dept. Agri., Bu. Ent. 

 Bui. 110, page 105. However, from these Syrphid eggs, young Syr- 

 phid larvse issued and grew to maturity, feeding on Aphis medicaginis . 



