Productive replication of the virus Hz-2V in female Helicoverpa zea leads to malformation of the host’s reproductive tissues and sterility of the adult moth. In addition, infected female moths produce 5 to 7 more times sex pheromone and attract twice as many male moths in flight tunnel experiments than do healthy females. This alteration of the development of reproductive tissues and the increased production of the pheromone in infected females creates conditions which favors virus replication in the insect host and the transmission of virus between individuals in the field. Analysis of the Hz-2V genome revealed the presence of a carboxylesterase (ORF-7) that codes for a 120 amino acid region which is homologous to the functional domain of the drosophila juvenile hormone esterase (JHE) gene. Upon examination of the level of JHE in female reproductive tissues during their development it was found that although JHE titers in tissues from healthy and infected insects followed the same pattern of decreasing as the insect matured the JHE titers in the reproductive tissues of last instar, agonadal females where significantly lower than those in tissues from healthy females. This is surprising since we also found that JHE levels in hemolymph, midguts and fat body from healthy and infected last instar females was the same. An examination of the reproductive tissues from infected insects revealed that alterations in the development of these tissues had already started in last instar larvae.