Oviposition preference studies evaluated the response of female mimosa webworms, Homadaula anisocentra Meyrick (Lepidoptera: Plutellidae) to chemical and tactile stimuli. Mimosa, Albizzia julibrissin Durazzini and honeylocust, Gleditsia triacanthos L. trees were utilized. A search for mimosa webworm eggs on honeylocust trees was conducted in four geographic areas. Females emerging from overwintering pupae in June showed an oviposition preference for mature foliage. The petiole and rachis were preferred over leaflets as oviposition sites. This was substantiated in laboratory studies, in which females laid more eggs on mature (over six weeks old) than on fresh (less than two weeks old) leaves from both hosts. From field observations and laboratory experiments, it was found that females preferentially oviposited on larval webbing when it was present. It was concluded that females were responding to a pheromone(s) associated with larval silk. Partial and complete ablation of the flagella demonstrated that the pheromone(s) was perceived by the antennae via contact chemoreception;Larval webbing rinsed with polar solvents eliminated or reduced oviposition on webbing. Rinsing webbing with a non-polar solvent had little effect on oviposition. Six-week-old webbing, rinsed or non-rinsed, was oviposited on as readily as was two-day-old webbing. The pheromone(s) most probably is a highly polar, non-volatile molecule. Extracts of larval mandibular and labial glands, webbing, silk, and macerated honeylocust leaves were pipetted onto various substrates. Oviposition was not elicited on any substrate or solvent combination. The pheromone probably is degraded or inactivated by polar solvents.