Heliconius erato (Nymphalidae: Heliconiinae) is an aposematic butterfly that have a tight relationship with Passiflora plants. It is known, that H. erato synthesizes de novo aliphatic cyanogenic glycosides, however recent biochemical studies indicates that the larvae of this species also sequesters both simple and complex cyclopentenoid glycosides from their host plants. In addition, during the larval stage H. erato metabolized the complex cyclopentenoid glycosides into simple cyclopentenoid glycosides. Analysis of amino acids in the adults revealed that these butterflies are storing not only cyanogenic compounds for defense, but also essential amino acids from metabolized cyclopentenoids gathered during the larval stage.