Honeydew secreted by homopterans has special effects on some natural enemies. On one hand, some natural enemies often use honeydew as one of sources of nutrient, which can improve the survival rate of nymphs, prolong the lifespan and raise the fecundity rate of adults. On the other hand, honeydew is often utilized as information substances for foraging behavior of some natural enemies. At the same time, artificial honeydew also has these effects on some natural enemies. Current knowledge in this field is re...