Enemies of White-Grubs. 



The natural enemies of white-grubs fall into three classes, namely, 

 animals (including- l)irds and lizards), insects (including mites and 

 Avorms), and plants (fungus and bacterial). A noted French natu- 

 ralist has said of the common European white-grub that "efficacious 

 animal parasites of the insect are unknown" (29). 



Fortunately, in Porto Rico, all three groups of parasites are 

 present ; yet as all of these are insufficient to keep white-grubs in 

 check, it is necessary — when other means of control fail — to supplant 

 these, or rather assist them, by the introduction of parasites not 

 already occurring here. 



ANIMAL AND BIRD ENEMIES OF GRUBS IN PORTO RICO. 



There are in Porto Rico no small mammals known to prey exten- 

 sively upon white-grubs or ]\Iay-beetles as do skunks in the United 

 States. Perhaps field mice and rats eat occasional specimens, but as 

 an agency of control they can be of no great economic importance. 



An attempt was made in 1913 by one of the sugar centrals of the 

 Island to introduce and acclimate the European hedgehog, quite a 

 number of which were brought over from Germany for the purpose. 

 ]Most unfortunately, they were liberated in a hot and arid part of 

 the Island, so different from their native humid and shady liabitat 

 that they did not survive. In confinement they ate ]Ma\'-beetles vora- 

 ciously when fed them, but were not seen to burrow deep enough 

 into the soil to reach the grubs ; and it is a question if they Avould 

 have proved of real economic importance as a control measure had 

 they become successfully established. 



In Porto Rico insect-feeding lizards are extremely al)undant. IMie 

 majority of these, which belong to the genus Anolis, are too small to 

 devour the larger ]\Iay -beetles. In addition they are diurnal in babit 

 and live entirely above ground, usually upon plant foliage or trees. 

 There is one large ground lizard, however, called "siguana" (Ameiva 

 exnl), which is largely burrowing in habit and which, it is believed, 

 feeds to some extent upon white-grubs and ^lay-beetles. It inhabits 

 the sandier soils, and by one close observer has been often seen de- 

 vouring changas, or mole-crickets. Certainly, white-grubs would be 

 far easier i)rey for it than the active changas ; and it is altogether 

 probable that they do constitute a part of its diet. 



Of birds, there are at least three species on the Island that Jirc 

 important enemies of the white-grubs and i\Iay-beetles, and a fourth 

 that is worthy of mention. These are. in the order of their importance 



53 



