N'ovember — December 1SS3.J 



PS2T//B. 



105 



rare in m\" own collections and in the 

 examples that have come under mv 

 observation. 



The youno- collector of insects learns 

 ver\- early the simple method of determi- 

 ning the sexes of his Luna, Poh phemus, 

 Promethca, and Cccropia pupae, and 

 of many other bombycid pupae, by 

 observation of the comparative breadth 

 of their antennal cases. 



A means by which the sex in the 

 pupae of tne spliingidae may be infalli- 

 bly named, was pointed out by me in 

 the Proceedings of the entomological 

 society of Philadelphia, iS6_|, v. 3, 

 p. 6^4. I have since foimd the same 

 characters applicable to the noctuidae 

 and to other heteroccra. 



Dr. C. V. Rilev, in the Transactions 

 of the academ\' of science of St. Louis, 

 1S73, vol. 3. p. 12S-129, and in the 6th 

 annual report of the state entomologist 

 of Missouri, for 1S73, 1^74, p. 131-132, 

 has described and figured sexual diller- 

 ences in the pupae of Prouiiha vitc- 

 casclla, consisting, mainly, in the great- 

 er length of the "dorsal projections" on 

 the several segments of the male, in the 

 length of the last two segments as com- 

 pared with tlu)se of the female (its 

 shorter iith and longer i3th), and in 

 its less rounded apex. He says : "sex- 

 ual distinctions are very rarely observa- 

 ble in chrysalids ; but after I had learned 

 to distinguish between them. I could 

 I'eadily separate the sexes in this case, 

 and my judgment was confirmed upon 

 tlie issuing of the moths." 



A few years ago I discovered an in- 

 teresting feature in the armature of the 

 species of Cossi/s. by which the sex 



may at once be determined. I have, 

 hitherto, withheld its publication, until 

 I had studied others of ourspined pupae 

 and could illustrate tliis fcatiu'e b\' proper 

 figures ; bvit the opportunity for this has 

 not been found, and I accordingly defer 

 no longer calling attention to it. that the 

 observations of others in possession of 

 more abundant material may supple- 

 ment the few that have been made by 

 me. 



It is known to lepidopterists that 

 most of the pupae of the species of 

 moths which in their larval stage live 

 in the interior of stems of plants and 

 trunks of trees (endophytes) , are armed 

 upon their abdominal segments with 

 transverse rows of teeth or spines, by 

 the aid of which, when they are in 

 readiness for their final transformation, 

 they gradually work their way through 

 the outer packing of their gallery and 

 the bark, project their anterior segments 

 to at least one-thirtl the entire pupal 

 length through the opening, and hold 

 themselves securely during the eclosion 

 of the moth. 



This useful armature in the cossiuac, 

 and in such of the aegeriidae as 

 I have had the opportunity of ex- 

 amining, consists of two rows of 

 spines upon most of the abdominal seg- 

 ments, dividing them, when seen in 

 extension, in three nearly equal parts. 

 In Cossi/s robiuiac, the species of the 

 rossinae with which we are probably 

 the most familiar, these rows occur on 

 the fiftli (the first stigmatal segment 

 posterior to the wing-cases) and the 

 following segments. 



In Cossus qiicrcipcrda alone of the 



