Chemical warfare in the Mount Olympus Cove area against the gypsy moth began at 6:05 a.m. Thursday as a helicopter sprayed about 300 gallons of the insecticide Bacillus Thuringiensis or B.t. on 1,190 acres east of I-215 between 50th South and 29th South and up Mill Creek Canyon to Tracy Wigwam Boy Scout Camp. Utah Department of Agriculture and U.S. Forest Service officials who observed the spraying said the weather couldn't have been much better with little or no wind. Spraying was halted at 7:30 a.m. while area children were traveling to school and resumed at 9 a.m. Most of the spraying was completed by 11 a.m. Two more spraying operations will be performed next Thursday and the following Thursday, weather permitting.