SOME OBSERVATIONS ON THE GENITALIA 

 OF LACHNOSTERNA. 



By W. P. Hayes and J. W. McColloch, 

 Kansas State Agricultural Experiment Station.* 



In making a study of the Lachnosterna of Kansas, the 

 writers have examined approximately 50,000 specimens for 

 specific determination. The works of Horn (1887) and Smith 

 (1889) were used in most of this work. Smith's paper was 

 especially helpful in making specific determinations, because of 

 the large series of figures illustrating the genital characters 

 which are now generally recognized as the best means of 

 separating the different species of this genus. Several species 

 of Lachnosterna occur in Kansas, however, that are not figured 

 in this paper, and in order to facilitate the identification of 

 them, illustrations of the genitalia were prepared. f 



Since many others are working with this group, it seemed 

 advisable to present these figures at this time in the nature of a 

 supplement to Smith's paper. It is not the purpose of the 

 writers to go into detail concerning the identification of the 

 various species, since Glasgow (1916) states that he is making 

 a thorough systematic study of the genus. Several discrepan- 

 cies in Smith's figures of L. corrosa, L. crenulata, and L. rubi- 

 ginosa are also discussed. In addition, a brief discussion is 

 made of specific and sexual determination in the pupal stage. 



DISCUSSION OF GENITALIA. 



Lachnosterna praetermissa Horn (Plate I, Fig. 7). 



This species is occasionally taken in Kansas, seven females 

 and four males having been collected in the vicinity of Man- 

 hattan. The figures of the male genitalia are presented by 

 Smith. The female genitalia approach that of L. implicata. 

 Superior plates are wanting and the pubic process is character- 

 ized by being heart-shaped, deeply cleft, slightly divaricate and 

 clothed with a sparse covering of short, erect hairs. 



*Contribution from the Entomological Laboratory, Kansas State Agricultural 

 College, No. 49. This paper embodies the results of some of the investigations 

 undertaken by the authors in the prosecution of project No. 100 of the Kansas 

 Agricultural Experiment Station. 



fThe writers wish to express their thanks to Mr. J. J. Davis for the determina- 

 tion of the specimens from which the Figures are prepared. 



75 



