The invention discloses a protective agent for ladybug eggs and application. The protective agent includes the following components by weight: 1-30 parts of nepetalactone, 0.5-25 parts of terpinolene, 0.1-15 parts of limonene, 0.1-15 parts of citronellal, and the balance water and additives. The protective agent provided by the invention contains substances with special smell, can produce a repellent effect on adult ladybugs adult and larvae and other predatory insects, thus protecting ladybug eggs from feeding during indoor ladybug raising and field release of ladybug eggs. The protective agent has the advantages of low cost, high efficiency, environmental-friendliness, human and animal safety, etc. The protective agent for ladybug eggs provided by the invention has broad industrialization prospects and simple preparation method, is especially suitable for large-scale breeding of ladybugs and large-scale utilization of ladybugs to control pests, and has broad economic, social and ecological benefits.