Eggs of the lesser grain borer, Rhyzopertha dominica (F.), are laid on the exterior of grain kernels. The eggs hatch and the neonate larva bores inside the kernel and completes development to the adult stage. Methoprene is an insect growth regulator (IGR) labeled for direct application to stored grains, but there are no data for eggs exposed on rough rice treated with methoprene. In this test, the low label rate of 1 ppm was sprayed on long grain rough rice (variety Cocodrie). A two-day-old lesser grain borer egg was put in each of 30 individual wells in a standard 96-well plate. Individual rice kernels were cracked by a scalpel blade, one cracked kernel was randomly put in each well plate containing an egg, and the plates were held at 32°C and 75 % relative humidity until adult emergence was completed. About 80-90 % of untreated-control eggs hatched and developed to the adult stage, with no visible morphological deformities, while only 20-30 % of lesser grain borer eggs exposed on the treated rough rice developed to the adult stage. Eggs either failed to hatch on the treated rice or the larvae died before they could penetrate the rice hull. Adults that did emerge exhibited various morphological deformities commonly associated with exposure to IGRs. Results show that eggs of the lesser grain borer laid on rough rice treated with methoprene will absorb enough of the insecticide to affect egg hatch and larval development.