Myllocerus undecimpustulatus undatus Marshall (Coleoptera: Curculionidae), also known as the Sri Lankan weevil, is becoming a major pest of ornamentals and tropical fruit trees in the southern USA, including Florida. Recent findings of this species in Florida citrus groves justify research into its biology and ecology. We studied morphological and sexually dimorphic characters of this species as an aid to rapid separation of sexes for studies aiming to identify semiochemicals that may be of value in management. Female weevils collected from the field in southeastern Florida were significantly larger than males in length of head, abdomen, and overall length. Females, but not males, have a characteristic black-gray marking extending from the ventral mesosternum to the second abdominal segment. Scanning electron microscopic images revealed that females had fewer ovate-to-obovate scales in this region of characteristic black-gray marking, and more plumose scales compared with males. Host choice and oviposition studies showed that Sri Lankan weevils prefer peach plants over weeds or grasses in peach orchards. Electroantennogram recordings with different peach volatiles identified peach odorants that can elicit significantly higher antennal responses. Both male and female Sri Lankan weevil antennae were highly responsive to these volatiles. Behavioral assays in olfactometers are underway to identify those semiochemicals that could be used as attractants or disruptants.