Our continued bioassay directed fractionation and purification of the mother liquor from Streptomyces griseus var. autotrophicus afforded an aromatic nitro compound, griseulin (1), with nematocidal and mosquitocidal activities. Griseulin was found to contain a 1,2-pyrone moiety similar to luteoreticulin as indicated by the carbonyl signal at 165.35ppm in its 13C NMR, lacked a furan ring, contained 3×CH3 and one OCH3, and gave the molecular ion at m/z 341 (C19H19O5N) with 100% intensity. Streptomyces spectabilis (ATCC 27465) and Streptomyces luteoreticuli or Streptoverticillium mobaraense (ATCC 25365) produced compound 1 when fermented under the same conditions. Bioassays showed compound 1 gave 100% mortality at 5 and 1 ppm, respectively, at 4 and 24 hours with Panagrellus redivivus, Caenorhabditis elegans and Heterodera glycines, and 100% mortality when tested with 4th instar Aedes aegypti larvae at 24 hours. As a novel aromatic nitro-containing compound with a 1,2-pyrone moiety, griseulin, a natural product, may function as a preliminary step to develop effective and safer compounds for the management of nematodes.