Nanoparticles (NPs) have been used as carriers and as protective coatings of labile substances with applications in pharmacy, medicine, and agriculture. This work focused on the development of an entrapment process for the protection of a natural larvicide extracted from Moringa oleifera (MO) seeds with cashew gum (CG) NPs as a wall material. CGMO NPs were characterized with regard to their size, morphology, kinetic release, thermal properties, and Stegomya aegypti larvae mortality. The result showed that the CGMO NPs presented average particle sizes ranging from 288 to 357 nm, with unimodal distribution. MO larvicide active principle loading varied from 2.6 to 4.4%, and the entrapment efficiencies were in the range 39.160.8%. In vitro release kinetics showed a Fickian diffusional behavior. The thermal stability of the CGMO NPs was related to the MO content, where their decomposition temperatures decreased with increasing MO active principle loading. Bioassays with third instar larvae showed that the mortality rate was related to larvicide loading and reached values up to 98 +/- 3% mortality. The CGMO NPs showed effective extract entrapment, with satisfactory larvicide effects even after 55 days of sample preparation and were effective as an improved and controlled release larvicide system. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012