Combinations of entomopathogenic nematodes Steinernema longicaudum X-7 and Heterorhabditis bacteriophora H06 with chlorantraniliprole, diflubenzuron, and imidacloprid insecticides at different rates for the control of the white grub, Holotrichia oblita Faldermann (Coleoptera: Scarabaeidae), were evaluated both in the laboratory and in peanut fields. In the laboratory, the combinations had a synergistic or additive effect on the second-instar larvae of H. oblita and caused faster mortality than one nematode species or insecticide alone. Heterorhabditis bacteriophora–chlorantraniliprole and H. bacteriophora–imidacloprid showed synergistic effects on the larvae. When higher concentrations of the insecticides were combined with nematodes, the stronger synergistic effects were found. In peanut fields, S. longicaudum–imidacloprid, H. bacteriophora–imidacloprid, or H. bacteriophora–chlorantraniliprole also showed synergistic effects against the larvae. The three nematode–insecticide combinations produced similar percentage reductions of the grub larvae and less percentages of injured legumes, compared with the chlorpyrifos treatment. Cost–benefit analysis showed that H. bacteriophora 5.0 × 10³ infective juveniles (IJs) per plant (equal to 7.5 × 10⁸ IJ ha^–1) combined with imidacloprid at the recommended concentration is a practical strategy for the practitioner to manage the white grubs in the peanut production.