A series of 2,2,3,3-tetramethylcyclopropanecarboxylates (R₃SnC₈H₁₁O₂), where R = methyl, ethyl, n-propyl, n-butyl, phenyl and cyclohexyl , have been synthesized by reacting the appropriate triorganotin and 2,2,3,3-tetramethylcyclopropanecarboxylic acid. Infrared and M�ssbauer spectroscopic results indicate that all the complexes, with the exception of the tricyclohexyl compound, are five-coordinated, while the tricyclohexyltin derivative is four-coordinated in the solid state. ¹H, ¹³C and ¹¹⁹Sn results indicate that all the complexes dissociate in solution and have tetrahedral structures. Adulticidal activities against the Anopheles stephensi and Aedes aegypti mosquitoes indicate that the Aedes aegypti were more tolerant to this series of compounds. In addition, an order of activity was observed based on the organic group attached to the tin atom.