Abstract: Traditionally, measurement of the acute toxicity of pesticide to honey bee has relied on LD50. However, the estimated lethal dose may only be a partial measure of the deleterious effects. In addition to direct mortality induced by pesticide, their sublethal effects on bee physiology and behavior must be considered for a complete analysis of their impact. This study focuses on two popular pesticides in Taiwan, imidacloprid and pyriproyfen. Assessment including significant behavioural effects and their longer-term consequences on colony survival and development will be conducted.