none A trypanosomatid flagellate, Herpetomonas sp., is recorded from an adult Mythimna separata (Walker) (Lepidoptera Noctuidae). Promastigote, paramastigote, and opisthomastigote stages measured 3.4-12 times 1.3-4.3 mu-m, Giemsa-stained, with flagella measuring 13.8-18.7 mu-m. A few amastigotes (3.9-8.3 times 3.7-6.7 mu-m) were also observed. Fourteen larvae fed with a suspension of flagellates were found later to be infected with the protozoan. No flagellate infections were found in the hymenopteran parasitoid, Apanteles ruficus (Haliday), or the hyperparasitoid, Trichomalopsis sp.