The temperature is among the abiotic factors that directly affect the developmental time and behavior of insects. The adaptability to climatic conditions is a key point for the success of mass-rearing and establishment of parasitoids in biological control programs. The objective of this study was to evaluate the developmental time and parasitism of Lysiphlebus testaceipes (Cresson) on Aphis gossypii Glover as host in different temperatures. The tests were carried out in climatic chambers at 15, 20,25 and 30 +/- 1[degree]C, 60 +/- 10% RH and 10h photophase. Parasitized nymphs of A. gossypii were kept individualized in petri dishes (6 cm of diameter) on a leaf disk (2 cm diameter) of chrysanthemum (Dendranthema grandiflorum Tzvelev) 'Yellow Snowdon' cultivar on a layer of agar. The developmental time of L. testaceipes was 26.9, 14.8, 11.3 and 12.2 days at 15, 20,25 and 30[degree]C, respectively. Parasitism rates were 76, 68, 65 and 40% at 15, 20,25 and 30[degree]C, and emergence rates were 80, 61, 62 and 14% at these temperatures. The combination of a low developmental time (11.3 days) and parasitism and emergency higher than 60% occurred at 25[degree]C, indicating that this temperature could be the most adequate for reproduction and establishment of L. testaceipes as a biological control agent of A. gossypii in protected cultivation. Animals and man; Control; Biological control; Life cycle and development; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Abiotic factors; Physical factors Lysiphlebus testaceipes (Aphidiidae); Control of; Aphis gossypii (Hemiptera); Development; Hemipteran hosts; Aphis gossypii; Temperature effects on parasitism & development, biocontrol potential implications; Temperature Aphis gossypii (Aphidoidea); Control by; Lysiphlebus testaceipes (Hymenoptera); Hymenopteran parasites; Lysiphlebus testaceipes; Temperature effects on parasitism & development, biocontrol potential implications none