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1920] Hays- McCol loch: Genitalia of Lachnosterna 77 



Lachnosterna corrosa Lee. (Plate I, Fig. 2). 



This species is frequently encountered in Kansas. According 

 to Glasgow (1916) L. affinis is synonymous with L. corrosa. An 

 examination of the specimens at hand show a variation in the 

 genitalia of both sexes from the illustrations presented by Smith 

 for either L. corrosa or L. affinis. In general they more nearly 

 approach the L. affinis type. In the males the claspers are 

 seen to be unsymmetrical. . The female genitalia are rather 

 characteristic. The inferior plates are large and are notched 

 to receive the greatly reduced and modified superior plates. 

 The pubic process is prolonged, divaricated and sparsely clothed 

 with hairs. 



Lachnosterna crenulata Froel., and Lachnosterna rubiginosa 



Lee. (Plate I, Figs. 8 and 9). 

 These two species occur in Kansas, the latter being one of the 

 most common species in the vicinity of Manhattan. Both 

 species are readily separated by the character of the lateral 

 margin of the thorax which is strongly crenate in L. crenulata 

 and but feebly so in L. rubiginosa. The genital organs of the 

 females of both species are rather simple and very similar. 

 The superior plates are fused along the median line and are 

 deeply emarginate. A small, tooth-like projection occurs at 

 the base of this emargination in L. rubiginosa. In Smith's 

 figures, this tooth-like process is shown in L. crenulata. The 

 superior plates are fringed with hairs of moderate length, the 

 hairg being more numerous in L. crenulata. 



SPECIFIC DETERMINATION IN THE PUPA. 



vSince it is often desirable to be able to identify the species 

 of Lachnosterna pupa^, the following observations are offered as 

 an aid of considerable value in the case of pupae that have 

 reached a somewhat advanced stage of development. As is 

 well known, the grubs are not specifically separable and it is 

 usually necessary to rear them to adults in order to make 

 deter iTiinations. Often they reach the pupal stage and die. 

 Fortunately, the genitalia develop at a comparatively early 

 stage and so lie within the body of the pupa that they become 

 visible through the pupal skin after the adult coloration begins 

 to develop. 



