Of 11 stains tested in the laboratory with larval Aedes aegypti, Giemsa at dosages of 6 mg/liter for 24 hr and 21 mg/liter for 3 hr proved most satisfactory for in-vivo staining. At these rates, Giemsa caused some mortality especially in first instars of Ae. vigilax, Ae. aegypti and Culex annulirostris but effectively was retained in all adults examined up to 3 days posteclosion. The method was deemed satisfactory for investigations of larval movement of Ae. vigilax, Cx. sitiens and Ae. alternans in salt marsh in southeast Queensland.