Seasonal Variation of Egg Size and Shape in Ypthima multistriata (Lepidoptera: Satyridae) in Relation to Maternal Body Size as a Morphological Constraint

To evaluate the role of the constraint on egg size imposed by maternal size, we examined the relationships between female body size and egg size and shape in the grass-feeding satyrine butterfly Ypthima multistriata Butler (Lepidoptera: Satyridae). In this species, larger and smaller mothers occur in the first and second generations, respectively. Egg size relative to maternal body size (relative egg size) was larger in the second generation than in the first generation. However, no body size constraint on egg volume was apparent in either generation. The degree of egg elongation (the ratio of egg length to egg width) increased significantly with relative egg size only in the second generation, but the correlation was quite weak. These results indicate that body size does not strongly constrain the determination of egg size; therefore, mothers have little need to elongate their eggs to respond to morphological constraints.