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Abstract Four phytoecdysteroids: (20-hydroxyecdysone-20, 22-monacetonide ( 1 ), 20-hydroxyecdysone ( 2 ), stigmasterol ( 3 ), gamma-sitosterol ( 4 ), were investigated for toxic effect against 3 rd /4 th instar larvae of Anopheles gambiae under laboratory conditions as individual compounds and in blends. The test larvae were treated with solutions containing the phytoecdysteroids of concentrations 1, 5 and 10ppm. The blends were prepared in the ratio of 1:1. Compounds 1 and 2 , isolated from acetone extracts of Vitex payos caused 100% mortality at 10ppm. Compound 3 isolated from acetone leaves of V. schiliebenii and compound 4 isolated from acetone stem bark of V. schilebenii also showed potent activity against the larvae at 10ppm. At the lower concentrations, abnormal mobility and impaired development was observed. Phytoecdysteroids (20-hydroxyecdysone-20, 22-monacetonide ( 1 ) and 20-hydroxyecdysone ( 2 ) are larvicidal against An. gambiae . stigmasterol ( 3 ), gamma-sitosterol ( 4 ) also show potent IGR activities against An. gambiae. Also addition of compounds 1 and 2 to stigmasterol ( 3 ) and gamma-sitosterol ( 4 ) seperately improved the activity of the two compounds.