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Youngest fully expanded leaves, from plants of M. Officinalis (L.) Lam. seeded at weekly intervals but harvested on the same day, were approximately 1.5 to 2.0 times as high in content of glucose, fructose, and sucrose at all stages of growth as leaves from comparable plants of M. infesta Guss. These plants varied in age from 3 to 14 weeks. Levels of glucose and fructose increased with increasing plant age in both species. Sucrose content increased in M. officinalis but decreased in M. infesta as the plants matured. When plants of approximately the same age were sampled at six different dates, the level of each sugar again was higher in young leaves of M. officinalis than in corresponding leaves of M. infesta at each sampling date. Evidence reported in this and preceding papers suggests that differences in sugar content may influence the degree of resistance or susceptibility of Melilotus leaves to feeding by the adult sweetc10ver weevil (Sitona cylindricollis Fahraeus), but that these differences apparently are not primarily responsible for the observed differences in resistance displayed by M. officinalis and M. infesta.