as enemies of grubs : (1) the Porto Riean blackbird or "mosambique," 

 Holoquiscalus brachypterus; (2) the bare-legged owl or "mucaro," 

 Gymnasio nudipes nudipes; (3) the little blue heron or "garza azul," 

 Florida caerulea caerulescens; and (4) the mangrove cuckoo or "pa- 

 jaro bobo, " Coccyzus minor nesiotes. In Bulletin No. 15 of this 

 Station, entitled "Birds of Porto Rico," by Alex Wetmore, the re- 

 sults are given of an examination of the stomach contents of these 

 four species of birds as follows (the figures being the per cent, of white- 

 grub and IMay-beetle remains to entire contents of all stomachs exam- 

 ined) : blackbird, 1.61 per cent. ; bare-legged owl, 2-4.4 per cent. ; 

 little blue heron, 1 per cent. : and mangrove cuckoo, .05 per cent. Of 

 twenty-three blackbird stomachs collected largely in cane fields under 

 cultivation, the proportion of white-grub and ]\Iay-beetle remains to 

 total contents was 9.47 per cent. Certainly, after a day of activity 

 of tile birds behind the plows in cane fields, the proportion would 

 be nuich higher than this. 



Another bird, kno^^m as the "ani." or "Juda bird," has been 

 often spoken of as eating white-grubs ; but the bulletin above referred 

 to does not give account of the finding of any white-grub or May- 

 beetle remains in stomachs of this species. And, moreover, common 

 as the bird is about cane fields, it is a rather shy species and is seldom 

 seen following the plows. 



The blackbird, or "niosanbique." is placed as the most important 

 bird enemy of white-grubs because of its great abundance in those 

 parts of the Island where the white-grubs are most injurious, namely, 

 in the arid coast districts. It is a very common sight to observe con- 

 siderable flocks of these birds following the plows and picking up 

 grubs when fields cleared of cane are being broken up. Figure 1, 

 of Plate VI. is from a photograph taken by the author at Santa Rita, 

 near Guanica Centrale, during the winter ])lowing season. By actual 

 observation and count, it was shown that over 90 per cent of the 

 grubs exposed to light t)y tbe plows are picked up by these birds, 

 so that the employment of peons to follow the plows and pick grubs 

 is (piite unnecessary in that district. When it is considered that a 

 bird is able to consume more than the equivalent of its own weight 

 of food in twenty-four hours, and that l)lackbirds during the plow- 

 ing season of five to six months subsist almost wholly upon grul)s, 

 one may a]>preciate the vast numbers of grubs that they consume. 



INSECT ENEMIES OF (JRUBS OCCURRING ON TIIK. ISI>.\\n. 



Among the insect enemies of the May-beetle larva' and related 

 white-grubs there arc at least nine species known to necui' on tiie 



54 



