METHOD: Life Cycle CONDITIONS: Field METHOD NARR: Newly emerged adults were released on field plots (both caged and uncaged) of tbr and ber. These adults were marked with paint. All life stages were monitored and counted to detine and number of eggs laid per mass. Overwintering on the two species was also assessed. Fecundity was measured using four different treatments. RESULTS NARR: All 4 instars developed more slowly on ber than on tbr. Beet plots resulting in population declines. Oviposition in field cages was much greater on tbr than ber. First generation larval survival was lower in ber plots than tbr plots. Larval survival on tbr decreased with increased egoccurred during the first instar on both hosts. On ber, oviposition increased in the 2nd generation. The winter survival was significantly lower on ber than on tbr. First generation of females raised on ber had lower oviposition. Tce in survival between larvae completing their third generation on ber than those on tbr. AUTHOR EXPLANATION: Authors indicate that CPB adapts to resistance of ber rather quickly (two generations).