A STUDY OF THE GENUS MONOXIA — BLAKE 149 



alike. There is a certain typical pattern, traces of which occur in 

 practically every species of Monoxia. When moderately developed it 

 consists of humeral, sometimes lateral, and usually subsutural infusca- 

 tions. From the slightly darkened sutural edges at the scutellum, 

 again before the middle, and sometimes again before the apex, a dark- 

 ened branch curves outward about a quarter of the way across the 

 elytron and then, in the case of the upper two branches, curves down- 

 ward parallel to the suture. The apical branch when present usually 

 enlarges at the end and often joins with the lateral darkening. In 

 the majority of the specimens, the suture is pale and only the ends of 

 the branches, running parallel to the suture, remain, forming what has 

 been described as the interrupted subsutural vitta. In certain heavily 

 marked specimens, on the other hand, the sutural and subsutural 

 vittae unite to form a wide, dark vitta common to both elytra. In 

 others, as in sordida, the branches take the form of rounded lobes. In 

 many all that remains of the branches is a series of spots in a line, 

 suggesting a vitta. Finally these spots may disappear, leaving the 

 elytra pale. The humeri are usually darkened and an indefinite lateral 

 darkening often occurs. Between this and the subsutural vitta are 

 irregular spots, often in a series. Although the elytral pattern is 

 fundamentally alike in ail species, some tend to be paler, for example, 

 certain Arizona species of arid areas, and some tend to be more darkly 

 marked. 



The question has been raised whether the species of this genus are 

 not in too active a stage of evolution to justify an attempt to reduce 

 them to order. For instance, in LeConte's species M. consputa, 

 angularis, and sordida specimens from different localities show appre- 

 ciable differences in minor features. This variation may indicate 

 that these species are still in the process of active evolution. It is 

 possible, however, to distinguish LeConte's species as variable \mits, 

 but at this stage of our knowledge of the genus it does not appear 

 advisable to do more than to describe the variation in the characters 

 of these species without distinguishing the forms by name. The 

 attempt to establish finer distinctions within the limits of these 

 species should be based on further study along biological lines. Other 

 species, such as M. schizonycha, puberula, and apicalis, are more 

 constant and clearly defined. For the differentiation of the species, 

 the pubescence and punctation, together with the shape of the pro- 

 thorax and aedeagus, and the presence or absence of depressions on 

 the elytra prove important characters. 



In this homogeneous group there is the greatest need for careful 

 biological study and the correlation of host plants. Apparently the 

 species may be roughly divided into two classes according to their 

 food plants, those feeding on Chenopodiaceae, both the -wild Cheno- 



