In a previous study on the reproductive biology of Eryngium yuccifolium Michx. (Apiaceae), a prairie species, it was found that in a native population 60 percent of the flower/fruit suffered herbivory versus one percent in a restored population. As a result of this finding several questions developed: do all native and restored populations of E. yuccifolium have this flower/fruit herbivory? can the size of E. yuccifolium populations influence the amount of flower/fruit herbivory? and do restored populations of E. yuccifolium of different ages have the same level of flower/fruit herbivory? To answer these questions, in 2001 data were gathered on 20 E. yuccifolium populations in Illinois. Ten of these populations occur in native prairies and 10 in restored prairies. Both native and restored populations ranged from a few individuals to thousands and all populations were in isolated prairie fragments. In the case of restored prairies, I used restorations that were from 6 to more than 25 years old. At each site, I collected three flower heads from 20 individuals and determined percent flower/fruit herbivory and percent fruit set. Herbivory was defined as presence of holes in the fruits and flowers or the entire ovary being eaten. Preliminary data analyses have shown that restored populations have lower percentages of flower/fruit herbivory than native populations. In addition, restoration age is an important factor associated with percent flower/fruit herbivory. A significant and positive correlation was found between restoration age and percent flower/fruit herbivory. The preliminary results of this study suggest that although it might take restored populations longer to resemble native populations, it is possible.

Key words: Eryngium yuccifolium, herbivory, native and restored populations