Anti-juvenile hormone activity, and the resulting cessation of feeding, has long been considered by the agricultural chemical industry as a means for insect control. Juvenile hormone esterase (JHE) contributes to the decline in JH titer at certain times during larval development. This chapter reviews the efforts made to develop a fast acting recombinant baculovirus insecticide by creating a virus which will express artificially high levels of JHE in the insect at inappropriate times. The findings are discussed in the light of our current understanding of the regulation of larval development and the role of JHE. Prospects for the newly developed, highly effective baculoviruses expressing modified forms of JHE are also considered.