The common black field cricket,Gryllus assimilis(Orthoptera: Gryllidae), damages young plants of red cedar,Juniperus virginiana(Cupressaceae); strawberry, Fragaria × ananassa (Rosaceae); sugarcane,Saccharum officinarum(Poaceae); teak,Tectona grandis(Lamiaceae); upland cotton,Gossypium hirsutum(Malvaceae); and, mainly,Eucalyptusspp. (Myrtaceae). The objective of this study was to investigate the biological and behavioral parameters of this insect in the laboratory and inEucalyptusspp. plantations in Inhambupe, Bahia State, Brazil. The incubation period and the viability ofG. assimiliseggs were 11.87 days and approximately 22%, respectively. The duration of the nymphal stage was 62.34 days with approximately 60% of the nymphs obtained in the laboratory being females. The average number of egg batches per female, eggs per female, and eggs per batch per female of this insect were 25.50, 862.17, and 34.65, respectively.G. assimilisfemales lived for 76.50 days in the adult stage, and 138.34 days in total, from egg through nymph to adult. Males produced three characteristic sounds: one for the marking of territory, one for courtship, and one when alone.G. assimilisfed primarily on weeds but, in their absence, it damaged youngEucalyptusspp. plants. This paper presents important data on the biology and behavior ofG. assimilis; this information may encourage additional biological research, laboratory rearing, and integrated management of this pest.