When phosphine is used according to label directions in a sealed grain bin, the fumigant is extremely toxic to all species of grain insects. Effective fumigation occurs when the phosphine gas is held in a sealed farm silo or bulk bin for long enough to kill the target insect pests. Phosphine treatment involves 7 – 10 days for better result under fumigation followed by 2 – 5 days ventilation and a further two days with holding period. Phosphine dosage is calculated on the volume of storage structure not the amount of grain in the silo or bulk bin. The temperature will affect fumigation length. Fumigated grain must be vented for the required time before it can be transported legally.