October, '16] KOCKWOOD: SPOROTRICHUM ENEMY OF ALFALFA WEEVIL 493 



Chairman H. J. Quayle: The mealy-bugs are probably more in- 

 fluenced by the wind. 



L. P. Rockwood: Are wind barriers of any use in preventing the 

 spread? 



Chairman H. J. Quayle: Yes, but they might have to be very 

 high as red spiders have been caught on a tank tower 50 feet high. 



The next paper will be presented by Mr. L. P. Rockwood. 



SPOROTRICHUM GLOBULIFERUM SPEG., A NATURAL 

 ENEMY OF THE ALFALFA WEEVIL 



By L. P. Rockwood, U. S. Bureau of Entomology, Forest Grove, Oregon 



The parasitism of insects by the fungus known at present as Spoj^o- 

 trichian globuliferiwi Spegazzini, although at one time seriously ques- 

 tioned and even denied by eminent mycologists, is now generally ac- 

 knowledged. That this fungus is probably the most efficient natural 

 enemy of the chinch bug, Blissus leucopterus, under conditions favor- 

 able for its growth and spread, is well known. However, very little 

 data has appeared as to the occurrence of the fungus as a natural 

 enemy of insects other than the chinch bug. We have long lists of 

 insects of various orders recorded as furnishing a sub-stratum for the 

 growth of this fungus, but few or no observations of the fungus as a 

 factor in the natural control of these insects. 



This fungus has come under my observation in connection with 

 various insect hosts both in the field and laboratory at various times 

 during the past two years. Its relation to the alfalfa weevil, Hypera 

 variabilis (posticus) Hbst., in Utah in 1914, is dealt with briefly in this 

 paper. 



Occurrence of the Fungus on the Alfalfa Weevil 



The fungus Sporotrichum glohuliferum Speg., was first found on the 

 alfalfa weevil near Salt Lake City, Utah, on March 14, 1914. It was 

 frequently met with and could easily be found on weevils and other in- 

 sects under alfalfa plants from that time until May. This was a time 

 of considerable precipitation and the ground in alfalfa fields was moist 

 to wet most of the time. The time of greatest abundance of the fungus 

 was April 21 to 29. At this time at least one weevil killed by the fun- 

 gus could be found under almost every plant examined. On April 

 29 this was particularlj^ true. On this date 11 weevils killed by the 

 fungus were found under one alfalfa plant covering an area of about 

 four square feet on a high bank outside the irrigated area. 



This early mortality of weevils caused by Sporotrichum glohulijerum 

 is undoubtedly of considerable importance as the death of the adults 



