Fall armyworm (FAW) is an economically devastating, invasive pest in Sub-Saharan Africa and can be a major pest in the Americas. This pest feeds on more than 80 plant species, including peanut, and threatens the food security of millions of people who rely on these crops in Sub-Saharan Africa. An integrated pest management strategy, including resistant crop cultivars, is needed to control FAW, since populations have been reported to develop insecticide resistance. Genetic sources of host resistance to FAW are limited in cultivated peanut; however, strong resistance to FAW was reported previously in peanut wild relatives. In this in vitro study, we tested diploid peanut relatives including A. ipaensis KG37006 (Ipa), A. duranensis 30060 (Dur), A. correntina 9530 (Cor9530), and A. correntina 9548 (Cor9548); allotetraploids including IpaCor95304x, IpaDur4x; F2 hybrids [A. hypogaea 13-1014 x IpaCor95304x]; and cultivated peanut lines A. hypogaea ‘13-1014’ and ‘Georgia Green’ for FAW resistance to identify valuable materials in our breeding program. FAW development was measured by survival, larval weight, larval stage duration, pupation, pupal stage duration, moth emergence relative to pupation, and moth sex. All allotetraploids showed promise as donors for FAW resistance. This FAW resistance was derived primarily from A. ipaensis, but A. duranensis was also identified as a source of resistance, though more moderate. A high level of heterogeneity was found in A. correntina 9530, which likely contributed to the variable performance of this species in the bioassay. Producing hybrids and allotetraploids with wild Arachis species does not guarantee that each derived line from these crosses will be resistant, and since these lines are segregating, selection for resistance is still needed.