specimen through its stages, but may succeed in doing so by the time 

 tlie next beetle season arrives." 



Outside of Europe, and the work done by Mr. Davis in Indiana, 

 tlie nearest approach to accuracy in establishing the length of life- 

 cycle of a beetle of the group Mehlonf hides is the work done in. 

 Mauritius on Fhijtahis sinithi by ^Ir. d'Emmerez rle Charmoy (6). 

 He determined the maximum and mininnim number of daj's required 

 for each stage of the life-cycle, but did not determine the length of 

 separate instars of the grub. 



So far as known to the writer, nothing lias been published here- 

 tofore on the larvcp of Phijllopliaga or related genera which estab- 

 lishes accurately the lengths of instars of the grub. 



Life-Cycles of White-Grubs. 



It has been kno"^^^l for a number of years that the common cock- 

 chafer of Europe. Meloloniha meloloniha, whose grub is the worst 

 white-grub pest of that continent, required a period of three years 

 to pass its life-cycle in the latitude of France and southern Germany, 

 and four years in the latitude of northern Germany. 



In the United States it has been taken for granted that certain 

 common species of P]iyUopJiaga, such as P. fusca and P. frntema, 

 because of the regular periodicity of their appearance m numbers 

 every three years, require that length of time to pass the life-cycle (7). 

 Certain other species in the States, appearing regularly at intervals 

 of two years, were supposed to require that length of time to undergo 

 the change from egg to adult (33). Very recently ]\lr. Davis has 

 definitely ascertained that out of eighteen species of I'hyUophaga 

 reared from egg to adult in the latitude of central Indiana eleven 

 of them have an invariable three-year life-cycle, one (Phyllophaga 

 tristis) has an invariable two-year life-cycle, three have a life-cycle 

 varying from two to three years, and two others a cycle varying from 

 three to four years (5). 



The establishment of the fact that all four Porto Rican species 

 of Phijllophago, as well as the single species of Phgtalus, require but 

 a year or somewhat less to undergo the life changes, will be somewhat 

 of a surprise to students of this group of insects. Vet it is what 

 should be expected in a tropical or sub-tropical climate. 



These facts are paralleled, in a measure, liy those established by 

 .Mr. De Charmoy with regard to the life-history of Phyialns smithi 

 in Mauritius — with the difference that he found the life-cj^cle of that 

 species to occupy somewhat over a year ((i). 



52 



