Selection process used to generate the green variant. Five to 10 orange adult Acyrthosiphon pisum (raised at 22°C) were placed on Vicia faba plants kept at 10°C. The aphid mothers were removed after 2 days, leaving the descendants. This process was repeated until a stable population emerged with a green phenotype (after 5 months). The original orange offspring did not reach maturation under these conditions. The population of cold-selected aphids with the green phenotype was propagated at 9°C for an additional year and then transferred to 8°C for continuous propagation (5 years).