The Oregon Department of Agriculture is investigating the die-off of thousands of honeybees in Sherwood.
KGW reports dead bees were found Sunday scattered along on Highway 99 at Sunset Boulevard.
State Insect Pest Prevention and Management specialist Pat Mitchell says there are many theories but the state won't know what happened until samples are completely tested.
There are agricultural fields nearby.
Last year, tens of thousands of bees were found dead in a Wilsonville shopping center. Two companies were fined for spraying pesticide that killed the bees.