yr-old plants tended to have greater leaf area than the 1-yr-old plants (mean SD = 111.7

+ 65.2 cm2 and 82.8 53.2 cm2, respectively).

 Most domatia (78.3%) contained ants. The frequency of unoccupied domatia was

 approximately twice as high for the 1-yr-old plants as for the 5-yr-old plants (28.8%, and

 14.3%, respectively). Aztecapittieri was the most abundant species (43.3%), followed

 by Crematogaster carinata (33.3%), Cephalotes setulifer (14.4%) and Pseudomyrmex

fortis (8.9%). Significantly more worker ants were present in domatia from 5-yr-old

plants than in domatia from 1-yr-old plants, but there was no effect of fertilization on ant

number (Table 3-3, Fig. 3-2). The number of worker ants present also varied

substantially according to which species occupied the plant (Fig. 3-3). Overall, Cr.

carinata had the most workers per domatium overall and was the only species to have

more than founding queens and a few workers present in domatia from the 1-yr-old

plants.

 The proportion of leaf area missing from the leaves surrounding each domatium

ranged from 0.02 to 0.45 (mean + SD = 0.12 0.09). The 1-yr-old plants tended to have

higher proportion of leaf area missing, as did the plants that were not fertilized-both of

these effects were marginally significant (P < 0.10). The number of ants, included as a

plant-level covariate in the model, significantly affected herbivory (Table 3-4). Linear

regression showed only a weak but significant negative relationship between ant number

and herbivory (R2 = 0.24, P < 0.0001), but the mixed model analysis showed that ant

presence and abundance were clearly important when plant age and fertilization were

included in the model. Although the effects of age and fertilization were not statistically

significant at the a = 0.05 level, examination of the data suggests that the 1-yr-old plants