From 1998 to 2001, the relationship between the proportion of tillers with >0 mummified aphids (P_tm) and the proportion of cereal aphids parasitized (P_p) was estimated on 57 occasions in fields of hard red winter wheat located in central and western Oklahoma. Both original (57 fields) and validation data (34 fields; 2001–2002) revealed weak relationships between P_tm and P_p, however, when P_tm > 0.1, P_p always exceeded the recommended parasitism natural enemy threshold of 0.2. Based on the relationship between P_tm and P_p, upper (P_tm1) and lower (P_tm0) decision threshold proportions were set at 0.1 and 0.02, respectively. We monitored cereal aphid populations in 16–25 winter wheat fields over time, and based on the upper and lower decision threshold proportions (P_tm1 = 0.1, P_tm0 = 0.02), predicted whether aphid intensities (# per tiller) would increase above or be maintained below selected economic thresholds (3, 9, and 15 aphids per tiller). Results of this validation study revealed that aphid intensity exceeded an economic threshold in only one field when predicted to remain below P_tm > 0.1, but aphid intensity reached a maximum of only four aphids per tiller. The sampling plan developed during this study allowed us to quickly classify P_tm, and independent of initial cereal aphid intensities, very accurately predict suppression of populations by parasitoids. Sequential sampling stop lines based on sequential probability ratio tests for classifying proportions were calculated for P_tm1 = 0.1 and P_tm0 = 0.02. A minimum of 26 tiller samples are required to classify P_tm as above 0.1 or below 0.02. Based on the results of this study, we believe that simultaneous use of aphid and parasitoid sampling plans will be efficient and useful tools for consultants and producers in the southern plains and decrease the number of unnecessary insecticide applications.