. 



INSECTS AFFECTING VEGETABLE CROPS IN PORTO RICO. 



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

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



COLEOPTERA. 



Diabrottca 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 Diabrotica 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. 1 



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" (Amaranthus 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 StaJL, 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 

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

 the case with the latter species, there is a marked difference in the 

 markings on the wing-covers. This difference is shown in figures 4 

 and 5 of Plate I. 



Adults of Cerotoma denticornis have been found feeding upon garden 

 beans and cowpeas, plants which have been reported on the main- 

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

 quite similar. Mr. Barrett, in his 1903 report (p. 448), mentioned 

 denticornis as being common. 



1 Van Dine, D. L. Report of the Entomologist. Sugar Producers' Association of Porto Rico. Ann. 

 Rpt. 3, p. 34, 1913. 



