The bioassay of ladybeetles was carried out on the petri dishes,on which the honeydew of tea aphid was distributed.The ladybeetles were released at the centers of the dishes one by one.Results showed that 2 types of honeydew,i.e.honeydew naturally secreted by tea aphids and honeydew concentrated after secreting,strongly attracted Coccinella septempunctata and 4 varieties of Leis axyridis. The searching and staying time prolonged significantly( P <0.01),with the increasing of the honeydew concentrat...