New Zealand's leading bee scientist is calling for warnings on the use of surfactants in chemical sprays.
Surfactants are ingredients added to sprays to help the chemicals penetrate plants.
Mark Goodwin from Plant and Food Research says there's generally a high level of awareness among New Zealand growers and contractors about the precautions needed to protect bees when spraying crops.
But he says supposedly bee safe chemicals can still be lethal if they have surfactants added to them.
"At the moment surfactants don't have to go through the same registration and safety testing that other chemicals do, unfortunately."
Dr Goodwin says New Zealand hasn't suffered the large scale unexplained bee deaths or colony collapses that have occurred in northern hemisphere countries.
He told an agricultural chemical and veterinary medicine company conference on Thursday that the part pesticides may be playing in those bee losses is still under debate, as many other factors including nutrition and the moving of hives also have an effect.