The side‐effects of plant protection products on beneficial arthropods have been studied by the Netherlands Plant Protection Service since 1974. Laboratory test methods were developed in the context of IOBC/WPRS forEncarsia formosa, a natural enemy of glasshouse whitefly,Trialeurodes vaporariorum.These methods were elaborated by EPPO into a sequential decision‐making scheme and published as an official EPPO guideline in 1989. The scheme includes a residual toxicity test on adults, a direct contact test on pupae, a persistence test on adults, all in the laboratory, and a field test. Following this guideline, the Netherlands Plant Protection Service tested and evaluated 107 pesticides at 307 concentrations over 10 years. Test details and complete test results are reported, including the risk assessments according to the EPPO scheme and according to the IOBC/WPRS conventions. These results are further summarized per type of pesticide, kind of test and risk classification. The efficiency of the scheme in classifying pesticide concentrations for risk toE. formosais analysed. The scheme was found to be reasonably practical and efficient except for pesticides in the range between safe and hazardous. Suggestions for improvement are given. Also the possible need for changing the original IOBC/WPRS‐criterion for harmlessness (effect<50%) is discussed. No reasons for lowering the criterion to 30% were found. The decision‐making scheme fits into the general approach for environmental risk assessment of plant protection products, developed recently by EPPO and the Council of