AbstractRomalea micropteracorpus cardiacum (RCC) contains large quantities of peptide material that is capable of eliciting strong hyperlipemic (maximum increase, 26 mg/ml; locusts) and hypertrehalosemic (maximum increase, 27 mg/ml; cockroaches) responses in test species. Calculation indicate that RCC contain more than an order of magnitude more bioactive material than eitherLocustaorPeriplanetacorpus cardiacum.R. micropteraitself shows no response to injections of synthetic locust adipokinetic hormone I (AKH I) at doses of up to 100 pmol, although injection of RCC at high concentrations (up to 1.0 gland‐equivalents) causes moderate hyperlipemia (maximum increase, 3 mg/ml). StarvedR. micropterado not exhibit the metabolic hyperlipemia observed in starvedL. migratoria, but starvation does block the RCC‐stimulated hyperlipemia. Neither fed nor starvedR. micropterashow a hypertrehalosemic response to RCC or AKH I. Reversed‐phase high‐performance liquid chromatography (RP–HPLC) shows the adipokinetic/hypertrehalosemic bioactivity to be concentrated in two peaks, which are present in the ratio of 6:1 Peak I: Peak II. Further RP–HPLC studies suggest that Peak II is identical to the adipokinetic hormone from the cricketGryllus bimaculatus, while Peak I appears to be a previously unknown n