eontined to the more humid sections of the north and west coasts — 

 which may further exphiin why white-gruhs are less abundant and 

 destructive in these sections than on tlie dr\- south coast, where there 

 are few or no Tachinid parasites or Pyrophorus beetles. An account 

 of the discovery of these two tlies will be found on page 37 of the 

 Second Report of the Board of Commissioners of Agriculture of Porto 

 Rico (30). The adult and pupal case of Vnjpiomeujenia aunfacirs 

 Wal., which is the commoner species, are shown on Plate VII. iigure 7. 



INTRODUCTION OF PARASITES. 



From many observations and estimates, it is evident that the inor 

 tality to white-grubs from parasites in Porto Rico is very low, and 

 that the native parasites are quite insufficient to cope with these 

 pests, which continue to increase wherever cane is grown. The only 

 hope in relieving this condition has seemed to be in the introduction of 

 other white-grub and May-beetle parasites from abroad. Among the 

 first elforts made in the artificial control of the white-grubs of the 

 Island, therefore, were attempts to introduce foreign parasit»^s, which 

 it was hoped would establish themselves successfully on the new host 

 grubs (27, p. 52). 



The logical field for securing white-grub and May-beetle parasites 

 was the United States, not alone because they are better known there 

 than elsewhere in the western hemisphere, but also because, in a large 

 territory like the American continent, parasites have wider distri- 

 bution, and necessary conditions for collection that cannot be encoun- 

 tered in one locality may be met in another. For convenience of 

 handling, collection of grub parasites is usually made of the cocoon 

 stage from the soil, and is therefore done during plowing time. 

 Plowing time in the States shifts from south to north with the ad- 

 vance of the season, thus permitting the collecting to extend over a 

 much longer period than would be possible in limited areas. 



Parasite introduction was initiated in 1911 by ]\Ir. D. L. Van 

 Dine, then entomologist of the Porto Rico Sugar Producers' Experi- 

 ment Statiton. His reports of the early progress of the work will 

 be found in the First and Second Reports of the Boartl of (commis- 

 sioners of Agriculture (29; 30). 



An entomological collaliorator was employed by the Board for 

 the purpose of collecting living white-grub parasites, or parasite 

 cocoons, in the States and shipping them to Porto Rico in living 

 condition. The position was first held by Mr. C. E. Hood, who began 

 work on June 16, 1911, and later by Mr. Geo. N. Woleott. The work 



57 



