2 Illinois State Laboratory of Natural History. 



depth of coloring of the costa and stigma varies considerably 

 in the same lot of specimens, in the majority of them being of 

 the normal piceous, but in occasional specimens becoming 

 lighter. From another lot of Ceratomia larvaa, there were ob- 

 tained August 1 of the same season, similar cocoons, the adults 

 from which began to emerge August 12, and all had issued 

 within a few days thereafter. Dr. Riley mentions (1. c.) hav- 

 ing bred this large variety from masses of cocoons spun regu- 

 ularly side by side, as were our specimens, but having no ribs 

 as ours have. 



MiCKOPLITIS MAMESTEiE, Sp. n. 



Under this name I describe a well-marked species bred 

 from the larvae of Mamestra pida., at Normal, in 1884. In a 

 breeding cage containing a large lot of Mamestra larvae there 

 were noticed July 2, two specimens, each having a peculiar 

 ribbed cocoon fastened transversely between the anal prolegs. 

 These cocoons were isolated, and August 23 there had emerged 

 from them the two Microplitis females here described. 



Cocoon. — 5 mm. long, 2 mm. wide. Reddish brown, cylin- 

 drical, Avith a pointed cap at each end, and about ten slightly 

 oblique ribs running longitudinally. Tough and without loose 

 threads. The cap forms a perfect circle, and in the specimens 

 at hand one on each cocoon had been entirely separated by the 

 insect before emerging. The corners are well developed, so 

 that a longitudinal section, without the caps, would he of the 

 form of a rectangular parallelogram. 



Described from two specimens found attached, singly, be- 

 tween the anal prolegs of larvte of Mamestra picta., Harr. 



Imago., 2. — Length, 3 mm. Black; antennae, mandibles, 

 and labram, reddish brown; palpi, and legs, including whole of 

 coxae, and more or less of the under side of abdomen, together 

 with a portion of the margins of terga of first and second ab- 

 dominal segments ferruginous; claws blackish. Wings hyaline; 

 tegulae, with inner portions of costa and nervures, approaching 

 ferruginous (being slightly more yellowish than legs), and outer 

 portion testaceous. Inner half of stigma same color as inner 

 portions of costa, nearly transparent; outer portions darker, 

 clouded. Antenn.e not quite as long as body; joints 3-15, 



