ART. 28 EEVISION OF DISONYCHA NORTH OF MEXICO — BLAKE 59 



Food plants. — Beet, spinach, Amaranthus. 



Remarks. — D. triangularis., a well-known enemy of sugar beets 

 and the largest of the dark-colored North American species, is read- 

 ily recognizable by the short, broad prothorax with its three black 

 spots arranged triangularly, the distinctly punctate elytra, and the 

 dark head and undersurf ace. 



DISONYCHA TRIANGULARIS MONTANENSIS, new variety 



Plate 7, Figxxbe 37 



Description. — Similar to D. triangularis in color and markings; 

 prothorax not so broad, with more rounded sides, elytra more finely 

 and sparsely punctate; aedeagus larger and somewhat differently 

 shaped. Length, 5 mm; width, 2.5 mm. 



Type (male).— U.S.N.M. No. 43653. 



Tyjje locality. — Assiniboine, Mont., collected by H. G. Hubbard 

 and E. A. Schwarz. 



Remarks. — Described from a single specimen. It is possible that 

 this is specifically distinct from D. tAangularis.^ although closely 

 related, since the shape of the prothorax and the sculpture of the 

 elytra are somewhat different, and the aedeagus, while of the general 

 shape of that of triangularis^ differs in several details. 



28. DISONYCHA POLITULA Horn 



Plate 7, Figure 40 



Disonycha polituJa Horn, Trans. Amer. Eat. Soc, vol. 16, p. 211, 1889 (New 

 Mexico and Arizoua ; type in Horn collection, Acad. Nat. Sci. Philadel- 

 phia ) .—Jacoey, Biol. Centr. Amer., vol. 6, suppl., p. 275, 1891. 



Description. — Slender, oblong oval (4.5 mm), with lustrous and 

 closely punctate green or blue elytra, the upper half of head also 

 dark with metallic luster, lower front and prothorax pale, under- 

 surface mostly dark, the abdominal margin, anterior femora, and 

 basal half of posterior femora pale. Head with interocular space 

 barely half width of head, carina slightly produced; a circle of 

 coarse punctures on each side about fovea near eye; occiput, front, 

 and usually tubercles dark with metallic luster, carina and lower 

 part of head, except dark labrum, pale. Antennae dark brown with 

 three basal joints paler; third point shorter than fourth or fifth, 

 which are subequal, the fourth longer. Prothorax nearly rectangu- 

 lar, slightly convex, approximately twice as wide as long, sides a 

 little arcuate ; surface shining, very finely, sparsely and indistinctly 

 punctate, entirely pale. Scutellum black. Elytra lustrous green or 

 blue, closely but shallowly and sometimes rugosely punctate; some- 

 what convex, sides parallel, humeri well marked, a short intrahu- 

 meral sulcus within. Body beneath lightly and indistinctly pubescent, 

 mesosternum, metasternum, and middle of abdomen dark shin- 



