Fig. 8(d) depicts another special event that two honey bees came in and went out at the same time. At the beginning, a honey bee intended to enter the beehive. After the bee interrupted the IR1, however, it crawled backward and left the beehive because there was another honey bee in the beehive tried to go out. In this case, the bee counting unit would wait for one second and expected that IR2 would also be interrupted. If IR2 did not transmit the interrupted signal to the bee counting unit, both IRs would be reset and wait for next incoming and outgoing events of honey bees. This mechanism was designed to prevent a wrong detection of honey bees’ outgoing and incoming behavior and ensure that the system could more accurately determine the honey bees’ incoming and outgoing activities. Combining these incoming and outgoing rules with the operation scheme of the bee detection system