Abstract Despite the increasing presence of metal nanoparticles in the biosphere as a consequence of their widespread use, knowledge about the impact of these nanoparticles on fauna, ecosystems and human health is far from completion. This is especially true for terrestrial invertebrates. Insects are environmentally exposed to nanoparticles by several ways, the ectopic contact being one of the most probable. The model insect Oncopeltus fasciatus , has been used in the present work for testing toxicity of nanoparticles present in a surface. Adverse effects of TiO 2 nanoparticles and Al 2 O 3 in nanoparticulated or bulk form on mortality, reproductive and embryonic developmental parameters have been analyzed after tarsal contact of adult individuals of O. fasciatus. Effects were monitored in the unexposed filial generation from control and exposed adults. In order to know the effect of the nanoparticles on the insect composition, measurements of protein and lipid content as well as lipid peroxidation were also performed. The results obtained indicate that the ectopic exposure to nanoparticles at 1 mg/cm2 (TiO 2) and 0.5 mg/cm2 (Al 2 O 3) did not induce lethal toxicity in O. fasciatus , nor did it modify any of the reproductive parameters. However, NPs-TiO 2 and Al 2 O 3 produced an increase in nymphal life span. In the parental generation NPs-TiO 2 increased protein content whereas NPs-Al 2 O 3 decreased it. Several effects were detected in the filial generation as consequence of parental exposure. NPs-Al 2 O 3 decreased protein content, NPs-TiO 2 decreased lipid content and Al 2 O 3 in bulk form diminished protein content and increased lipid peroxidation. Responses observed in the individuals of the filial generation demonstrate the existence of trans-generational effects of NPs-Al 2 O 3 and NPs-TiO 2. Graphical abstract Unlabelled Image Highlights • Oncopeltus fasciatus acquired Ti and Al metal oxide nanoparticles by contact. • TiO 2 nanoparticles increased the days to reach adulthood from first instar nymph. • Biochemical composition was altered in parents and/or offspring. • Oxidative stress evidences were not found but for bulk Al 2 O 3 in the offspring. • Trans -generational effects have been demonstrated. [ABSTRACT FROM AUTHOR]