AbstractTwenty‐one synthetic compounds, containing one or more furan rings, were demonstrated to possess anti‐juvenile hormone (AJH) activity as evidenced by their induction of premature metamorphosis in the milkweed bug,Oncopeltus fasciatus(Dallas) by contact, topical application or fumigation. The ED50of the four most active analogs required to induce precocious metamorphosis from 3rd‐instar nymphs by residue contact in a Petri dish compared favorably with that of precocene II (6,7‐dimethoxy‐2,2‐dimethyl 2H‐chromene) a naturally occurring phytochemical AJH. Precocious metamorphosis was fully reversible by co‐treatment with juvenile hormone (JH III) or JH analogs, demonstrating that the observed AJH activity resulted from an induced deficiency of j