that these stages of the different species may be as easily separated 

 as are at present the adults, will also be presented in another article. 

 The desire at present is to present the life-cycles of the Porto 

 Rican Melolonthids ; to facilitate the separation of the adults of the 

 species, where heretofore they have been hopelessly confused : and to 

 present certain facts in regard to their insect, fungus and bactei'ial 

 enemies that liave come to light in the course of experiments. 



What WIhite-Grubs Are. 



All beetles pass through a metamorphosis consisting of four stages, 

 egg, larva, pupa, and adult, two of which, egg and pupa, arc resting 

 stages and the other two, larva and adult, active stages. The growth 

 of the insect is attained during the larval stage; which means that 

 during this stage the most food is consumed, and hence the most 

 damage committed. It is with the larval stage of the May-beetles 

 and "hard backs," known locally as "caculos, " that we are con- 

 cerned. During this period they gain tlie name of white-grubs (or 

 ''gusanos blancos") through their white color, and theii- luiliit of 

 grubbing in the soil. 



As the term is used in its broadest sense, white-grubs are con- 

 sidered as including the larvie of all the injurious Lamellicorn l)eetles 

 of the family Scarahaeidae (3). The word is often used in the United 

 States in a more restricted sense, as referring to the grubs or larvte 

 of the May-beetles, since these in the States far outiuimber rdl (ttliei- 

 white-grubs combined (4). 



White-grubs may be known from larva? of other beetles by the 

 following characteristics: (1) subterranean habits, living entirely in 

 tunnels in soil or decaying vegetable matter, and moving about very 

 little; (2) by liaving the body bent roundly toward the ventral side, 

 so that the ends nearly meet, hence poorly adapted to inovi'ment 

 above ground; and (3) by their bodies being thick, soft, and usually 

 glossy white or yellowish with sparse hairs, with a brown, chitiiioiis 

 head and strong mandil)les ada})ted for chewing roots aiul soil, and 

 with six well-developed legs not used for walking. 



White-Grubs Injurious in Other Regions. 



. Larva^ of Scarabaeid beetles are practically universal in tlicir 

 occurrence as pests, being everywhere known as white-grubs. TI103* 

 are particularly destructive, and often multiply in alarming innnberH. 

 in parts of the world where cane is grown, clue to eonditions wliich 

 greatly favor their development in such localities. Besides Porto 



49 



