IlSrSECTS AFFECTING VEGETABLE CEOPS IN POKTO RICO. 5 



plant, turnip, and cabbage are most affected," and that the water- 

 melon, bean, sweet potato, and yautia are seldom or never attacked. 



COLEOPTERA. 



DiABROTicA BiviTTATA Fab. and D. iNNUBA Fab. 



These two chrysomelid beetles occur in abundance on cucumber, 

 squash, and melon, especially on the flowers. They quite closely 

 resemble Diahrotica vittata Fab. in appearance and habits, and those 

 authors who have referred to vittata as being present on the island 

 have apparently failed to differentiate between the species. 



DiABROTICA GRAMINEA Bal. 



This chrysomelid beetle is very common in Porto Rico. Mr. Van 

 Dine has reported the adults as feeding on the leaves of sugar cane 

 to a slight extent.^ 



The beetles are bluish-green in color and about one-fourth of an 

 inch in length. So far as the writer has observed, the injury is most 

 severe on corn and okra, which are, in fact, the only two plants of 

 this group upon which the writer is certain that they feed, although 

 they have been observed feeding on the flowers of cowpeas, the fruit 

 of Solanum nigrum var. americanum, and the foliage of "jobo" 

 (Spondias lutea) and "bledo" {Amarantlius spinosus). 



The injury to corn is apparently confined to the silk of the ear and 

 the blossom spike. On these parts of the plant the beetles congregate 

 in great numbers, and the results of their feeding are very apparent, 

 especially on that portion of the silk which, ordinarily projecting 

 from the tip of the husk, is completely destroyed. On okra they feed 

 upon the blossoms and the young leaves. 



An assassin bug, Zelus rubidus Stal., has been taken with a beetle 

 of this species impaled upon its beak. 



Cerotoma denticornis Oliv. 



In appearance this beetle resembles the bean leaf-bettle (Cerotoma 

 trifurcatd Forst.), which also occurs in the United States, and, as is 

 lh(5 case with the latt<ir species, there is a marked difference in the 

 markings on the wing-<^;overs. This diff(!i-cncc is shown in figures 4 

 and 5 of Pluto I, 



Adults of (kroUmuL drmticornis have bo(ui found r(M>.ding upon garden 

 lK',an.s and cowyKuw, plants which hav<^ Ixuui nvportc^l oji tlie main- 

 land as food plants of trifurcata. The habits of the two species are 

 quite similar. Mr. Barrett, in his IDO.'i report (]). 448), mentioned 

 fierUicorjiis nn being common. 



' Van Dine, D. L. Report ot tho Enl«molo«l.st. Sugar Producers' Association of Porto Illco. Ann. 

 "l't-3, p. ai, 101,''.. 



