\textit{Nasutitermes aquilinus} is an arboreal termite that exhibits polymorphic apterous castes, including workers and soldiers varying in size according to their sex and age. This study aimed to determine internidal variation on morphometry of the apterous castes in \textit{N. aquilinus}. A total of 198 apterous individuals was collected from two nests (1 and 2) and 12 measures were taken for each individual. A principal component analysis was performed to separate the insects into groups and the differences among these groups were evaluated using the PCA scores in a two-way ANOVA (factors: group and nest), followed by a TukeyHSD test. The analyses were performed in R. The results showed that the PCA separated the individuals into eight groups: larvae1, larvae2, minor and major workers, minor and major presoldiers, minor and major soldiers. The PC1 was responsible for 84.10% of separation among the groups (F = 888.5; df = 8,185; P < 0.001) and PC2 for 9.75% (F = 605.1; df = 8,185; P < 0.001). The variation between nests was significant for minor and major workers and presoldiers using the scores of PC1 (F = 453.5; df = 1,185; P < 0.001) and for major soldiers using the scores of PC2 (F = 175.7; df = 1,185; P < 0.001). The individuals from nest 2, which was headed by 14 neotenics, were significantly larger in size. No reproductives were found in the nest 1. This internidal morphometric variation might be related to the reproductives that give origin to the apterous individuals. Funding: CNPq.