30 PRELIMINARY REPORT ON ALFALFA WEEVIL. 



high in front, and adjustable in the rear. The top was of light sheet 

 iron bolted to the frame. 



Oil was pumped from a barrel in the conveyance to which this 

 machine was attached and forced through a rubber hose into a supply 

 pipe which fed the nozzles and burners underneath. The oil under 

 pressure came forth from the burners as a mist of fire blowing into the 

 stubble and against the ground. 



The sheet-iron cover served to hold the heat down while this oven 

 passed slowly over the surface. In its unperfected state the machine 

 did effective work and offered ideas of value, warranting the construc- 

 tion of more efficient burners. 



In fields where there was a clean stand of alfalfa stubble this 

 machine did very well in burning vegetation and destroying all insect 

 life above the surface of the ground. Where many weeds, especially 

 dandelions, were present, the insects found protection under the green 

 leaves. Where parts of fields were burned over, the unburned area 

 showed no growth for several weeks on account of the continued 

 weevil attack. The burned area turned green within a very much 

 shorter time. 



REDUCTION IN QUALITY OF HAY CAUSED BY THE ALFALFA 



WEEVIL. 



While studying the alfalfa weevil on various farms in the Salt Lake 

 Valley during the month of April, 1911, it was found that many farm- 

 ers, through a shortage of forage, were feeding the weevil-injured 

 hay of the first crop to their horses. This hay contained so many 

 old cocoons and was so dusty from larval excrement and dead bodies 

 of weevil larvae as to render it unfit as feed for horses. On several 

 occasions horses were observed coughing from the effect of this dust. 

 In fact, many farmers consider the first crop from severely infested 

 fields almost valueless as horse feed. 



On June 12, 1911, at Alpine, Utah, when the new hay from the first 

 crop was fed to work horses these began coughing almost immediately 

 after starting to feed upon this injured hay. The hay contained 

 large numbers of dead weevil larvae, some still on the skeletonized 

 leaves and some in the freshly spun cocoons. On September 13 hay 

 from the first crop, in stack', was examined at Lay ton, Utah, and 

 found to be very dusty, containing many dead weevil larvae and also 

 pupae. 



NATURAL ENEMIES. 



The natural enemies of the alfalfa weevil consist of vertebrates and 

 invertebrates. The former have been studied by assistants of the 

 Bureau of Biological Survey, and a list of species observed to attack 

 the weevil is given herewith. 



