Survival of the nematodes Heterorhabditis bacteriophora Poinar and Steinernema glaseri (Steiner) Wouts, Mracek, Gerdin & Bedding formulated in oil emulsions of avocado (Persea americana Mill.), castor bean (Ricinus communis L.), chia seed (Salvia hispanica L.), and mamey (Mammea Americana L.), in concentrations of 30 and 50% with 50 ± 5 and 100 ± 10 infective juveniles per milliliter were evaluated. H. bacteriophora and Steinernema websteri (Cutler & Stock) in P. americana to 30% were applied to adults of Scyphophorus acupunctatus Gyllenhal in doses of 500 and 1,000 ± 10 infective juveniles per insect. Most H. bacteriophora in oil emulsions of 30 and 50% of P. americana survived for 96 hours, 41.5 and 25.5%, respectively. In bioassays, the dose of 1,000 ± 10 infective juveniles of H. bacteriophora in oil emulsion of P. americana to 30% was 100% effective in killing S. acupunctatus 72 hours after being applied. S. websteri survived 120 hours. Formulation of entomopathogenic nematodes in vegetable oils improved survival and effectiveness over S. acupunctatus in a laboratory.