INTRODUCTION OF FINGUS ENEMIES. 



Simultaneous with the introduction of insect parasites of white- 

 giuhs into Porto Rico, Mr. Van Dine initiated an attempt to intro- 

 duce certain entomogenous fungi that are known to attack white- 

 grubs and beetles related to the JMay-beetles in other regions (27; 29) 

 Cultures were received both from Europe and from Hawaii, the 

 species of most importance from the former place being Botryfis 

 tcncUa (or Isaria densa) , which is reputed to have been used with 

 so iiuich success at one time against the larvae of Melolohtha in France 

 (29, p. 42). 



From cultures received from Hawaii one species, that known as 

 the Sarnoan fungus, or green muscardine fungus, Metarrhdziinn ani- 

 sopliae, was succeessfully established on the Island, and large num- 

 bers of May-beetles were infected by means of soil inoculations (29) 

 (See PI. IV, figs. 7, 8, 9.) It was later learned that a local form 

 of this fungus had already existed on the Island prior to the intro- 

 ductions from Hawaii, as grubs and Ijeetles infested with the fungus 

 were found in parts very remote from Avhere liberations of spores 

 had been made (12; 30). 



Several liberations of the spores of MetarrJiizium have been made 

 by the pathologists of the Station, ]Mr. J. R. Johnston and ]\Ir. J. A. 

 Stevenson, tlie spore material having been grown in large cabinets 

 on a scale surpassed only by the extensive liberations of Metarrhiziion 

 against the frog-hopper in Trinidad. The results of these liberations 

 have been somewhat variable (25). 



IMethod of Rearing Grubs. 



Because of their subterranean habits, white-grul)s are vi'vy <lifH- 

 eult to rear to maturity, and to observe their molts. I jiving in tunnels 

 in the soil, they are apt to be injured or set back in growth l)y being 

 disturbed. Difficulty rests also in their requiring so long to reach 

 maturity, their life-cycles in many cases covering a period of more 

 than a year, which promotes the possibility of their succumbing to 

 fungus and other diseases contracted through artificial means. 



It is possible that the difficulties of rearing white-grubs in con- 

 finement are less felt in the tropics than in temperate cjimalfs be- 

 cause of there being no period of cold weather tlirough wliidi the 

 grubs must be given special care and treatment. This advantage, 

 however, is in part counteracted by the increased activity of certain 

 parasitic fungi and other diseases that attack the gi-ubs in warmer 

 climates. 



60 



