THE BROAn-IJKAN WEEVIL. 21 



RECOMMENDATIONS. 



Only uninfestecl or treated horse beans should be used for seed. 

 All horse beans used for seed which are infested with the Ijroad-bean 

 weevil either should l)e treated with carbon disulphid or held over 

 in tight receptacles until the second year, when the weevils will all 

 be dead. 



Carbon disulphid should be used at from 7 to 10 pounds per 1,000 

 cubic feet, for at least 24 hours, in a box, barrel, or room as air-tight 

 as it is possible to get. The smaller amount is effective in perfectly 

 tight receptacles, but the larger amount should be used if the fumiga- 

 ting box or room is not tight. The liquid should be placed in a shal- 

 low pan at the top of the box or poured over the seed. 



Infested seed which has not been treated and is held in warehouses 

 or barns near broad-bean fields, except that held over for seed until 

 the second year in tight receptacles, should be disposed of or fed be- 

 fore the planting season. 



Badly infested seed should be ground up in feed mills immediately 

 after harvesting. 



Planting should be delayed until as late as possible, preferably 

 after March 1. In the dryer and hotter localities where this is not 

 possible, it is especially important to plant only seed which is unin- 

 festecl or has been treated to kill the weevil. 



All growers of horse beans should cooperate in carrying out these 

 measures. 



SUMMARY. 



Broad-bean growing has been handicapped seriously by the pres- 

 ence of the broad-bean weevil {Bruchus rufbinanus) . 



Although the first record of this insect's establishment in America 

 was in 1909, it probably has been here since about 1888. 



It is found in the entire broad-bean section of California. 



The weevil not only lowers the value of the beans but has greatly 

 reduced the acreage planted to that crop. 



The insect has but one generation a year and does not breed in dry 

 beans. 



The Qgg stage is from 9 to 18 days; the larval stage, 10 to 15 

 weeks; the pupal stage, 7 to 16 days; and the adult stage, 1 to 8 

 months. 



Eggs are laid on the green bean pods in the field from the middle 

 of March to the middle of May ; the larvse reach maturity from 

 August to October, while adults can be found from August to the 

 following June. 



Germination of infested beans is from 20 to 40 per cent less than 

 that of uninfested beans. 



