This regulation establishes a time-limited tolerance for combined residues of the insecticide avermectin B<INF>1</INF> and its delta-8,9-isomer in or on bulb onions. This action is in response to EPA's granting of an emergency exemption under section 18 of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) authorizing use of this pesticide on bulb onions. This regulation establishes a maximum permissible level for residues of avermectin in this food commodity. The tolerance expires and is revoked on December 31, 2009.