Lepidopteran pests pose a heavy burden on global agricultural industries, causing significant economic costs due to losses in many crops such as soybean, chickpea, cotton, and tomato (Zalucki et al., 1994). Although a variety of chemical and eco-friendly insecticides have been employed since the 20th century (Casida and Quistad, 1998; Windley et al., 2012), environmental and health concerns as well as resistance development have reduced the overall number of insecticides available for controlling lepidopteran pests. It is therefore essential to discover novel eco-friendly insecticides and arachnid venoms have been hailed as a promising source. Arachnid venom peptides feature desired insecticide characteristics like selectivity, potency, stability, and cheap and up scalable recombinant production methods (Windley et al., 2012). While arachnid venoms are directly injected into their prey (Lüddecke et al., 2021), it has been questioned whether arachnid venom peptides would be orally active, which is a requirement for their use as agricultural insecticides. To simulate the field-scenario of insecticides being applied by spraying or directly expressed in transgenic plants, we developed an oral leaf disc assay against the globally significant lepidopteran pest species Helicoverpa armigera. Soybean leaf discs were covered with insecticide solution and neonate H. armigera larvae were then introduced to feed on the leaves with toxicity being regularly monitored for up to 3 days. Using this assay, we observed dose-dependent effects for the commercial insecticides imidacloprid and Bacillus thuringiensis (Bt) toxin. We then employed the assays for screening a diverse panel of 133 arachnid venoms yielding an 8% hit rate for venoms exhibiting at least 50% lethality. The advantage of a leaf disc assay over feeding artificial diets is that it provides a more realistic evaluation of the oral toxicity while still enabling fast and high-throughput screening.